The Politics of Supreme Court Nominations: A Theory of Institutional Constraints and
Choices
Author(s): Bryon J. Moraski and Charles R. Shipan
Reviewed work(s):
Source: American Journal of Political Science, Vol. 43, No. 4 (Oct., 1999), pp. 1069-1095
Published by: Midwest Political Science Association
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ThePoliticsofSupremeCourtNominations:
A TheoryofInstitutional
Constraints
and Choices
BryonJ.Moraski, UniversityofIowa
Charles R. Shipan, UniversityofIowa
can attempt
touse hispower
Whena vacancyoccurson theSupremeCourt,thepresident
in ordertobringtheCourtin linewithhisownpolicypreferofnomination
strategically
to do so. First,he
facestwoconstraints
whenattempting
ences.However,thepresident
Courtmedian.
justicesandtheexisting
bythepresenceofcontinuing
maybe constrained
bytheSenate,whichmustapprovehis nominee.In this
Second,he maybe constrained
underwhicha president
thatexaminestheconditions
paperwe developandtesta theory
can,anddo,
in his choiceof a nominee.Ourresultsshowthatpresidents
is constrained
behavestrategically
withrespectto SupremeCourtnominations.
1. INTRODUCTION
In recentdecades,vacancieson theSupremeCourthaveappearedapeverytwoyears.BecausetheCourtplayssucha centralrole
proximately
in politicsandpolicymaking,
presidents
place a greatdeal ofimportance
on fillingthesevacancieswithnomineeswhowillproducea Courtthat
whilewe
on theiragendas.Surprisingly,
however,
looksmorefavorably
havelearneda greatdeal inrecentyearsaboutSenatevotingon Supreme
Courtnominations,
analysishasbeendoneon presiverylittlesystematic
of thejudiciaryin
dents'choicesof nominees.Giventheinvolvement
of the
and thecentrality
area of policymaking
nearlyeveryimportant
ofthechecksandbalancesin our
nomination
processto an understanding
tounderstand
theprocessbywhichpresiitis imperative
politicalsystem,
dentsselectnominees.
Our
Courtnominees.
Herewe analyzepresidential
choicesofSupreme
SuthattheSenatealmostalwaysapproves
starting
pointis theobservation
onlyfournominees
Sincetheturnofthecentury,
premeCourtnominees.
havebeenapproved-a
havebeenrejectedbytheSenate,whilefifty-five
PoliticalScience
at the1996 meetingof theSouthern
Earlierversionsofthispaperwerepresented
Associationandthe1997 meetingoftheAmericanPoliticalScienceAssociation.We wouldliketo
thankChrisAchen,MattGabel,Michael Giles,JohnHuber,Eric Lawrence,Ed Schwartz,Jerry
andBeckyMortonforhelpful
Sorokin,KatieTenpas,andespeciallyKathyBawn,CaryCovington,
We also wouldliketo thankTimGroseclose,GregAdams,and George
comments
anddiscussions.
us withideologyscores.
Krauseforproviding
AmericanJournalofPoliticalScience,Vol.43, No. 4, October1999,Pp. 1069-1095(1999 bythe
MidwestPoliticalScienceAssociation
1070
BryonJ.Moraskiand CharlesR. Shipan
successrateofgreater
than93 percent.1
Giventhistremendous
rateofsuccess,we believetheimportant
toexamineis howthepresident
question
decideswhatkindofnominee
he shouldchoose.
Ourprimary
is in determining
howthepoliticalcontext
interest
influIn particular,
encesnominations.
we lookto see whether
theexistenceof
other
political
thepreferences
ofthoseother
institutions,
andthe
institutions,
constitutionally
prescribed
sequenceoftheprocessaffect
thepresident's
choice.Wealso explorewhether
otherfactors,
suchas presidential
popularityandyearsremaining
in office,
affect
nominations.
Ourgoal is todeterminewhichofthesefactors
influence
thepresident's
choice.
2. THESUPREME
COURTANDTHESEPARATION
OFPOWERS
Theselection
ofa Supreme
Courtjusticebeginswithan opening
onthe
Courtduetoeither
thedeathorretirement
ofa justice.Whena vacancyoca candidate,
curs,thepresident
nominates
andthecandidate
is confirmed
or
a
vote
of
rejected
by majority
theSenate.Iftheposition
ofchiefjusticebecomesvacant,
thepresident
botha sitting
mayeither
nominate
justiceforthe
anda newassociatejustice,orhemaynominate
a newchiefjustice
position
fromoutsidetheCourt.2
eventhough
thepresident
Surprisingly,
playsa majorrolein thisproof
cess,mostrecentsystematic
analyses SupremeCourtnominations
have
focusedmainly
ontheSenate'sconfirmation
vote.3
Wehavelearnedthatthe
Senatevoteis morelikelytobe conflictual
whenthenominee
is lessqualifiedor is ideologically
outofstepwiththeSenate(Cameron,
Cover,and
Segal 1990b).We havealso seenthatthetiming
ofthenomination
(Segal
1987)andthepreferences
ofconstituencies
andinterest
groups(Overbyet
al. 1992;Segal,Cameron,
andCover1992;CaldeiraandWright
1998)influencetheSenate'svote.Additional
evidencesuggests
thattheideologyofthe
departing
justicealso maymatter
(Ruckman
1993).
'The fournomineesrejectedbytheSenatewereJohnJ.Parkerin 1930,ClementHaynsworth,
Jr.,in 1969,G. HarroldCarswellin 1970,andRobertH. Borkin 1987.Despitebeingrejected,
these
nomineesall receiveda gooddeal ofsupport
whentheSenatevoted,ranging
fromBork's42 percent
toParker's49 percent.
In additiontotheserejections,
twoothernomineeswerenotconfirmed
bythe
hisnomination
Senate:Johnson
withdrew
ofAbe Fortasforthepositionofchiefjusticebeforevotingtookplace,andtheSenatetookno actionon Johnson's
nomination
ofHomerThornberry.
2WilliamRehnquist,
forexample,was an associatejusticewhennominated
andconfirmed
for
thepositionofchiefjustice.His predecessor,
Warren
Burger,
was noton theCourtwhennominated
andconfirmed.
3A wealthof descriptive
materialon howpresidents
choosefromamongpotentialnominees
canbe foundina number
ofstudies.Forrecentexamples,see Abraham(1991),Maltese(1995), and
Silverstein(1994). For systematic
evaluationsof presidentialnominations
see Massaro (1978;
1990), Cameron,Cover,and Segal (1990a), Watsonand Stookey(1995), and Nemacheckand
Wahlbeck(1998).
SUPREME COURT NOMINATIONS
1071
Thesestudiesoftheconfirmation
votetreatthechoiceofa nominee
as
exogenous.Putsomewhat
differently,
although
manyofthesestudiesasindeciding
sumethatmembers
oftheSenatebehaverationally
howtovote,
forthepresident.
theydo notmakethesameassumption
Instead,
thestrategic mannerin whicha president
mightchoosea nomineeis ignored.
Yet
mostnominees
receivea largemajority
ofvotes,whichsuggests
theneedfor
a careful
analysisofthenominationstage.Lopsidedconfirmation
votesare
almostcertainly
dueinparttothecareful
consideration
givenbypresidents
tothechoiceofnominees,
consideration
thecongivenwithan eyetoward
firmation
vote.
How mightthepresident
behavestrategically?
GiventheCourt'skey
rolein setting
publicpolicy,thepresident
willwanta Courtthatshareshis
ideology
andthuswillnominate
someonewhowillbringtheCourtcloserto
hispreferences.
Atthesametime,however,
thepresident
is constrained
by
institutional
features
ofthenomination
process.First,theSenatehas the
or denythepresident's
powerto confirm
choice,whichmayforcehimto
takethepreferences
oftheSenateintoaccountwhennominating
someone
fora seaton theCourt.Second,depending
on theconfiguration
ofpreferencesofcontinuing
thepresident
justicesandhisownideology,
maynotbe
Inableto shift
theCourtso thatitcompletely
shareshisownpreferences.
hisidealpoint.
distance
toward
stead,hemaybe abletomoveitonlya short
3. THE NOMINATIONGAME
nominee
The requirement
thattheSenatemustapprovea president's
on thenomination
placesa certainstructure
game.In thefirststage,a vanominates
someonetofill
cancyoccurs;in thesecondstage,thepresident
thatvacancy;and in thethirdstage,theSenatevoteson thepresident's
nominee.4
Because thepresident
knowsthattheSenatewill voteon his
oftheSennominee,
whenhe makeshischoicehewilltakethepreferences
ate intoaccount.Giventheconstitutionally
prescribed
sequenceof this
on theassumption
thatactorsarerationalandforwardgame,andrelying
looking,
we canmodelthenomination
gameusingtheequilibrium
concept
ofsubgame
perfection.5
4Forreasonsdiscussedlaterin thispaper,we omittheJudiciary
Committee
fromouranalysis.
5Analysesusingthesameequilibrium
conceptto examinethepresident's
appointment
power
includeNokkenand Sala (forthcoming),
Hammondand Hill (1993), and Snyderand Weingast
(1994). Like SnyderandWeingast,we modeltheappointment
processas occurring
alonga single
Nokkenand Sala forthcoming)
dimension.
Althoughsomerecentanalyses(mostnotably,
indicate
thata seconddimension
forSupremeCourtconfirmation
mightbe empirically
relevant
voting,
preof the
vious studieshave demonstrated
thata singledimensionprovidesa usefulapproximation
morecomplicated
multi-dimensional
realityof theappointment
process(e.g.,Segal,Cameron,and
Cover1992;Cameron,Cover,andSegal 1990b).In addition,
single-dimensional
analysesaremore
1072
BryonJ.Moraskiand CharlesR. Shipan
If theSenaterejectsthenominee,
thegameends.In otherwords,we
treatthisas a single-period
game.Severalarguments
providejustification
forfocusing
ona single-period
game.To beginwith,as ouranalysisdemonofinteresting
andtestable
that
strates
below,therearea number
implications
in ordereventually
derivefroma single-period
model.6Furthermore,
to
tounmodelthenomination
processas a multiperiod
game,itis usefulfirst
derstand
thesingle-period
game.
Mostimportantly,
a single-period
gameis a veryplausiblerepresentaofreasons,thepresident
will
tionofthenomination
process.Fora number
notwantthegametocontinue.
Thepresident's
publicapproval
andstanding
withtheSenatemaysuffer
fromsucha rejection.
Thus,thereis a lossofpoliticalcapitalassociated
withputting
forth
a nominee
whois rejected.
Morehas to expendthiscapitalin a losingcause,whereasit
over,thepresident
be spentmoreprofitably
onother
might
otherwise
policyissues.Inaddition,
thereare time-related
costs.If histermin officeis ending,thepresident
notgetanother
chancetonominate
someone.
theSenate
might
Alternatively,
might
changeandbecomemoreinhospitable
tohispreferred
nominees
(e.g.,
thepresident's
partyoftenloses Senateseatsat themidterm
election).Fiwilllosetimein whichhe couldhavea Courtthatpronally,thepresident
moreinlinewithhispreferences.
Becauseofthesecosts,he
ducesoutcomes
hasa strong
tonominate
incentive
someonewhowillbe approved.
Wemakethefollowing
inthegame.First,
all players
have
assumptions
perfect
andcomplete
information
aboutthepreferences
ofotheractorsand
thesequenceof thegame.Second,playershaveEuclideanpreferences.
Third,theactionsofplayersaredriven
bytheirpreferences
overpolicy,an
onbelow.Fourth,
we elaborate
assumption
recognizing
thatthesize ofthe
forwelloveronehundred
Courthasremained
at ninemembers
years,we
ordiestheCourtwillhaveeightmembers.
assumethatafter
a justiceretires
we assumethatiftheSenatedoesnotapprovea nominee,
Fifth,
theseatremainsopen,andtheCourtfunctions
witheightmembers.
Finally,
inthespatialmodelspresented
belowwe also assume,without
lossofgenerality,
that
thepresident's
idealpointis totheleftoftheCourtmedian.
Thegamebeginswhena seatopensontheCourt.7
Priortothecreation
ofthevacancy,
themedianofthenine-member
Courtis equaltotheposition
tractable,
theoretically
and empirically.
We agreewithKrehbiel's(1996) assessment
that"multidimensionalinstitutional
theoriesaremorelikelyto yieldexamplesthangeneralpropositions,
andas
such it is difficult
to discernwhetheror how thegeneralproperties
of multidimensional
choice
withininter-branch
institutional
settings
differ
fromtheunidimensional
results"(1996,34).
6Asingle-period
approachalso facilitates
empiricaltesting
bynarrowing
thepotential
equilibriumpredictions
(Morton1999).Allowinga gametobe repeatedoftenproducesmultiple
equilibria,
whichcouldprevent
themodelfromyieldingclearandtestableimplications.
7Wetreattheexistenceof a vacancyon theCourtexogenously.
In a morecompletemodel,vacanciescouldbe endogenous,
as someopeningsoccurdue to strategic
considerations
(Squire1988;
Hagle 1993).
SUPREME COURT NOMINATIONS
1073
Figure1. SupremeCourtwitha Vacancy
|
J
|
J2
|
J3
l
l
l
l
l
l
J4
J
J5
J6
J7
J8
Ideology
ofthefifth
justice.Oncethevacancyoccurs,however,
thischanges.In Figure1,eachoftheeightremaining
justices(J1through
J8)is locatedalonga
scale accordingto his or herideology.Becausetherearenowonlyeight
members
on theCourt,no singlejusticeoccupiesthemedianposition.Inovertheinterval
stead,thepolicyoutcomewillbe a lottery
J5],andwe
1J4,
ofthisinterval,
J= (J4+ J5)/2,
tobe considered
therefore
allowthemidpoint
theCourt'smedianafter
a vacancyoccurs.
Oncea seatopens,thepresident
hasanopportunity
tonominate
a potentialnewjustice.Weassumethatthepresident,
whoseidealpointwe denote
byP,is motivated
bypolicyconcerns.
Thus,hewantstomovethemedianof
theCourtas close as possibleto hisownidealpoint.In otherwords,the
president
wantsto minimize
thedistance
betweenP andJ*,whereJ*is definedas thelocationofthenewmedianifthepresident's
nomineeis approvedbytheSenate.8
Consider
first
whatthepresident
woulddo intheabsenceoftherequirementthattheSenateconfirm
his nominee.In sucha case, ofcourse,the
stillcannotsimply"choose"a newmedianfortheCourt.Rather,
president
he is constrained
bythepresenceofeightsitting
justices.Becauseofthese
continuing
justices,thenewmedianwillremainin theinterval
J5],re1J4,
ofthenominee.
ifthe
oftheideological
Morespecifically,
gardless
position
choosesa nomineeN suchthatN < J4,thenthenewmedian,J*,
president
whichtheSupremeCourtreachesdecisions;
8Wedo notexplicitly
modeltheprocessthrough
instead,we relyon themedianvoteron theCourtto providea proxyforitsdecision-making
outcomes.Somewhatsurprisingly,
verylittleattention
has beenpaid to theaccuracyof usingthemetheCourt'spolicypositions.
We believethattherelevanceofthemedianvoter
dianvotertorepresent
itsuse.
to Courtdecisionmakingdeservesfurther
attention,
buthereuse threearguments
to support
we relyon Black's medianvotertheorem,
whichholdsthatin a votingbody
Firstandmostsimply,
whosemembers
canbe arrayedalonga linewithsingle-peaked
theoutcomewillbe the
preferences,
medianvoter.Second,although
somestudieshavedemonstrated
thatthechiefjusticecan actstrategicallyin assigning
opinions(MaltzmanandWahlbeck1996),itremainstruethatboththechiefjusticeandtheopinionauthormusttakecaretosatisfy
themedianmember
oftheCourt,forwithout
the
ofthatmember,
support
theycannotsustaina majority.
Thus,changesinthemedianlead monotoniclose observers
callyto changesin theCourt'soutput.Finally,andmostimpressionistically,
recognizetheimportance
ofthemedianmember
oftheCourt.WhenNationalJournalrecently
published
a listof themostimportant
politicalactorsin Washington,
SandraDay O'Connor andAnthony
Kennedy-usuallyat or nearthemedianon theCourt-made thelist,butJusticesRehnquistand
Scalia didnot.See "TheWashington
100,"NationalJournal,
June14, 1997.
1074
J.Moraski
andCharles
R.Shipan
Bryon
willbe equaltoJ4.Similarly,
ifN > J5thenJ*= J5;andifN is locatedinthe
=
then
J*
interval
[J4,
J5],
N.
We maintain
thatthepresident's
choiceis motivated
the
bytheeffect
willhaveontheCourt'smedian.Thepresident
nominee
willchoosea nomineewho,ifapproved,
willbringtheCourt'smedianclosertohisownideal
point.He candothisbychoosing
a nominee
whoseidealpointis closetohis
own(i.e.,N = P). Thus,whatis keyfrom
ourperspective
is thatthepresident
can achieve both of these goals-minimizing both IP - J*1and IP - NI
simultaneously.
Consider
Figure1,keepinginmindthatforthemoment
we arestilligtheroleplayedbytheSenate.Ifthepresident
noring
is locatedtotheleftof
J4,hewillwanttomovethemediantoJ4andcando so bychoosing
a nomineesuchthatN = P. Similarly,
ifP > J5,anynomineesuchthatN > J5will
movethemediantoJ5;andthepresident
againwillchooseN = P. Finally,
whenthepresident
is locatedintheinterval
J5],choosinga nomineeat
1J4,
hisownidealpointwillcausethenewmediantobe locatedathisidealpoint
(i.e., N = P will lead to J*= P).
In otherwords,regardless
ofhislocationrelative
totheexisting
Court
thepresident
canmovethemediantoward
hisidealpointbychoosmedian,
ingN - P.9In somecaseshe is constrained
bythepresenceofthecontinuingjustices,inthesensethathe canonlymovethemediana portion
ofthe
distanceto hisownidealpoint.Butin all cases,bychoosingN = P he obtainsthebestpossiblenewmedian.
Whathappens
whenweintroduce
theSenateintothemodel?Obviously,
thepresident
nowmusttakeintoaccountthepreferences
oftheSenatebeforedeciding
ona nominee.
Hisgoalwillbe tochoosethenominee
whowill
producethebestnewmedianand whoalso willbe approvedbytheSenate.10
Whether
theSenateconstrains
thepresident,
however,
dependson the
ofinstitutional
As themodelwe developin the
configuration
preferences.
nextsectiondemonstrates,
therearethreedistinct
regimes,
andwhichvariablesaffect
theposition
ofthenominee
dependson whichregimeexists.In
thefirst
tworegimes
discussed
below,theSenateandpresident
agreeonthe
direction
of changeforthemedian(althoughtheymaydisagreeon the
amount).In thethirdregime,theydisagreeabouteventhedirection
of
change.
9ChoosingN = P therefore
is a weaklydominantstrategy
forthepresident.The president
could,ofcourse,chooseothervaluesofN. However,bychoosingN = P he notonlymovesthemediantowardhisidealpoint,he also increasesthelikelihoodthatfuture
medianswillbe locatedclose
tohisidealpoint.
10WeassumethattheSenatealso is motivated
primarily
bypolicyconcernsandis mostconcernedwithhowthenewnomineewill,ifconfirmed,
affect
themedianon theCourt.We base this
on thedemonstrably
assumption
strongrelationship
betweensenators'policypreferences
andtheir
voteson SupremeCourtnominees(see, e.g.,Cameron,Cover,andSegal 1990b;Ruckman1993).
SUPREMECOURTNOMINATIONS
1075
3.1 Regime1: Unconstrained
Presidential
Power
First,
consider
thecase whereS < P < J,as illustrated
inFigure2a. The
president
knowsthatifhenominates
someonewhoshareshisideology(i.e.,
N = P) andthatpersonis confirmed,
thenthenewmedianwillbe equaltoJ4.
In addition,
he knowsthattheSenateprefers
anynewmedianJ*suchthat
J*< J.Sincea nominee
J*= J4,thepresident
locatedatP produces
knowsthat
theSenate,whichprefers
sucha nominee.
Ofcourse,the
J4toJ,willapprove
Senatemight
a nominee
prefer
locatedclosertoS thantheonethepresident
is willingtoputforward.
Sinceitprefers
theSenate'shand
J4toJ,however,
is forced:
byrejecting
thepresident's
itwoulddecreaseitsownutilnominee,
ofhavingthefirst
ity.Thepresident,
byvirtue
theSenate
move,canpresent
withanoptionthat,
whilenotperfect,
is oneitprefers
tothestatusquo.
in thisregimethepresident
Moregenerally,
is unconstrained
bythe
Senate;bychoosinga nomineeathisidealpointhe also movesthemedian
closerto theSenate'sidealpoint.Putsomewhat
differently,
anynominee
likeswillcreatea newCourtmedianthatfallswithin
thatthepresident
the
Senate'swinset.Thisholdstruewhenever
S < P < Jandalso usuallywhen
Figure2. Presidential
Nominating
Regimes
2a: Unconstrained
President
(Regime1)
S
P
J
J4
2b: Semi-Constrained
President
(Regime2)
P
I
~~~~I~~
1
J4
Is
1
S
2c: FullyConstrained
President
(Regime3)
P
J
S
1
J
1076
BryonJ.Moraskiand CharlesR. Shipan
P < S < J,withtheexceptionoftheconditiondiscussedin thenextsection.11
In effect,when the presidentand the Senate are on the same side of the
Courtmedian,thepresidentis almostalways unconstrained
by the Senate
position,and N will be a functionof P,butit will notbe a functionof S or J.
3.2 Regime2: Semi-Constrained
President
If theSenate is locatedcloserto themedianof theSupremeCourtthan
is thepresident(i.e., IJ- SI < IJ- PI), thepresidentmay nothave as much
poweras he does in Regime 1. More specifically,
ifP < S < J,S > (J4+ J)/2,
and P < 2S - J,thepresidentwill no longerbe able to presentthe Senate
witha take-it-or-leave-it
offerand be confident
thattheSenatewill takeit.12
To see this,considerFigure2b. If thepresidentchooses a nomineesuchthat
N = P, thenthenew medianwouldbe J*= J4.The Senate,however,prefers
Jto J*and therefore
wouldrejectthenominee.In fact,theSenateprefersany
to
of
point theright Is, whichis definedas Is = 2S - Jand is theSenate'sindifference
pointwithrespectto theCourtmedian,to J.
As opposed to Regime 1, wherethepresidentis constrainedby neither
the Senate's ideal pointnorthemedianof the Court,herethepresidentis
constrainedby a combinationof thetwo.Whatnomineecan thepresident
choose in orderto obtainthebestpossiblenew median?Workingbackward,
we can see thatthe Senate will approveany nomineethatyieldsa median
thatis closerto S thanis J.The presidentthenknowsthatthebesthe can do
is to choose a nomineewho will producea new medianat Is. He can do so
by choosinga nomineesuchthatN = Is. Hence,in thisregime,thepresident
has to nominatesomeonewhose positionis determined
by thecombination
of theideal pointsof theSenate and theCourt.He is semi-constrained;
that
is, he can choose a nomineewho will bringtheCourt'smediancloserto his
own ideal point,buthe cannotdo so by choosingN = P, and he cannotmove
themedianall theway to J4.
3.3 Regime3: FullyConstrained
President
Finally,thepresidentand theSenatemightbe locatedon oppositesides
of theCourt'smedian,as depictedin Figure2c. In thisregime,thepresident
and theSenatedisagreecompletelyabouttheideologicaldirectiontheCourt
shouldtake.Indeed,anyattempt
by thepresidentto movethemediancloser
to his ideal pointwill be rebuffed
by theSenate; and theSenate will never
I"When S < P < J,P is alwaysin theSenate'swin set,and thepresident
can alwayschoose
N = P.
'21notherwords,iftheSenateis closertoJthantoJ*andthepresident
is farther
fromS thanS
is fromJ,thenthepresident
is semi-constrained.
SUPREME COURT NOMINATIONS
1077
see a presidential
nomineewho is likelyto movetheCourt'smediantoward
S. There is a standoff,and the only outcome thatwould please both the
presidentand the Senate would be a nomineelocated at J. Regardlessof
whether
thedistancebetweenJand S is smallor large,as longas P and S are
on oppositesides of Jthepresidentwill befullyconstrainedin his abilityto
movetheCourtmediancloserto his ideal point.
EquilibriumOutcomes
The precedingdiscussiondemonstrates
thatwhile P, J,and S each are
important
determinants
ofthelocationofN, theirimportance
is a function
of
thespecificconfiguration
ofpreferences.
More explicitly,
themodeldemonstratesthatthereare threedistincttheoretical
regimes:one in whichN is a
functionof P, one in whichN is a functionof Is (whichin turnis a function
of S and J),and finally,
one in whichN is a functionof J.
Figure3 depictstheequilibriumoutcomesas a functionof the Senate
median.HoldingP and Jconstant,we see thatwhenS < P, theoutcomewill
be equal to P, regardlessof thelocationof S. Similarly,whenS > J,theoutcome willbe J,regardlessofthelocationof S. OnlywhenS is locatedto the
rightof (J4+ J)/2(i.e., themidpointof theinterval[J4,J]) does thelocation
oftheSenatemedianhavea directinfluenceon theoutcome.Similarfigures
couldbe drawnin whichP is allowedto varywhileS and Jare heldconstant
or whereJis allowedto varywhileP and S are heldconstant.In each figure
we would see thatwithinone regimethevariableof interestwouldhave an
effecton theoutcome,whilein theothertworegimesit wouldnot.
Figure3. Nominee'sIdeologyas a FunctionoftheSenate'sLocation
Nominee's
Position
J_
I
/1
3
3~~~~~~~~~egime
PI,
Regime1
P
Reg.2
LocationofS
J4J
1078
BryonJ.Moraskiand CharlesR. Shipan
This theoreticalfinding-thatdifferent
variablesare influential
in differentregimes-guides our empiricalapproach.In particular,the theory
of theempiricalmodel:
pointsto thefollowingspecification
N = Do+ PI*DI* P + P2* D2* IS + P3*D3* J+ E,
(1)
whereDI D2, and D3 are dummyvariablesindicatingthenatureof theregime.'3As thetheoretical
modeland theempiricalspecification
in Equation
1 makeclear,thenominee'spositionis affected
by eitherthepresident'sideology or the Senate's indifference
pointor the Court's median. It is not,
however,a functionof all of thesevariablesat thesame time.Whethereach
variablemattersdependson thelocationof S relativeto J and P. In effect,
inwheredifferent
then,thisadoptstheapproachof switchingregressions,
14
conditions.
dependentvariablesmatterunderdifferent
4. MEASURING
INFLUENCES ON THE NOMINATION
To examinethechoice of SupremeCourtnominees,we considerall justices nominatedto the SupremeCourtbetween 1949 and 1994 (i.e., from
Tom Clark throughStephenBreyer).This sample is relativelysmall,with
onlytwenty-eight
observations,and it is limitedin time.1 However,since
theseweretheonlynomineesforwhomwe couldobtaindataforall thevariables,thisproblemcould notbe avoided.'6
Our dependentvariable,whichfollowsfromour theoreticalmodel,is
theideologicalpositionof thenominee.To operationalizethisvariablewe
use the ideology scores developedforSupremeCourtnomineesby Segal
and Cover(1989). Segal and Coverderivedthesescores,whichare meantto
be predictiveof a justice's futurebehavior,froma contentanalysisof preconfirmation
editorialsaboutthecivillibertiesand civilrightstendenciesof
thenominees.Like ADA scores,thesepredictedscoresrangefromzero to
13Moreformally,
D, = 1 if S < P < N or if P < S < N, S < (J4+ J)/2,and P < Is, otherwise
1if P<J<S,
DI=0;D2= 1 ifP<S<N,S<(J4+J)/2,andP<Is,otherwiseD2=0;andD3=
otherwise
D3 = 0.
14The switching
regimesregressionapproachis especiallyvaluablewhenwe do notknow
whichregimeexists(e.g.,Lee and Porter1984). In ouranalysis,thelocationof thevariousactors
29.
spellsoutwhichregimeexists.See also footnote
15Another
potential
problemis thatwe cannotobserveall thepeoplethata president
chooses
nottonominate.
Instead,we makethereasonableassumption
thatthepresident
is allowedtochoose
froma setofpotential
justiceswhosepreferences
rangeacrosstheideologicalspectrum.
Fora perceptiveanalysisthatincludespeoplewhowereconsidered
butnotnominated,
see Nemacheckand
Wahlbeck(1998).
16The limiting
variableis theideologyof electedofficials.
ADA scoresextendback to only
1947,andW-NOMINATEscoresforthepresident
extendbacktoroughly
thesametime.
SUPREME COURT NOMINATIONS
1079
andonebeingthemostliberal
one,withzerobeingthemostconservative
forthisvariableandfor
thedescriptive
statistics
ideology.
Table1 presents
we discussbelow.
othervariables
ADA scoresof
To measure
theideologyoftheSenate,weusetheyearly
oftheSenate.We adjustthesescoresaccording
tothe
themedianmember
Levitt,
andSnyder(1999),
developed
byGroseclose,
methodology
recently
andcompresses
thattheADA scaleshifts
whichcontrols
forthepossibility
orexpandsovertime.
lessstraightforward.
ofpresidential
ideology
is somewhat
Measurement
a president's
parOneoptionwouldbe tousea dummy
variable
todesignate
andthus
measure,
however,
Weprefer
tousea moredifferentiated
tisanship.
byexamining
eachpresiusepresidential
ADA scores,whicharecomputed
of
dent'spositions
on thevotesADA usesto calculatescoresformembers
Congress(Zupan1992).As withtheADA scoresfortheSenate,thepresidentialideologyscoresalso rangefromzeroto one,withzerobeingmost
conservative
andonemostliberal.Andas withtheSenateADA scores,the
ADA scoresarecomputed
yearly
andareadjusted.
presidential
WhileADA scoresand thenominees'ideologyscoresbothcan be
exists.ADA
problem
scale,a potential
alignedalongthesamezero-to-one
in ordertodemonstrate
ofideology,
scoresaregeneralmeasures
computed
ofCongress.
ofeachmember
theoverallliberalorconservative
tendencies
andcivil
The nominees'scores,on theotherhand,focuson civilliberties
thanADA scores.Yet,therearerearights
andthusaremoreissue-specific
sonstousethemtogether.
First,
justicescastfarmorevotesincivilliberties
of
casesthaninanyotherpolicyarea.Thus,a goodportion
andcivilrights
ofthesemorespecific
scores.Second,at
theiroverallideologyis comprised
correlated.
thecongressional
level,ADA scoresandACLU scoresarehighly
bythird
partiestolocatepoattempts
Third,bothtypesofscoresrepresent
conservative-to-liberal
dimension.
liticalactorsalonga similarzero-to-one,
In theend,we maintain
thatitremainsthebestoption.The onlypreconofnominees'
scores,and
firmation
measures
ideologiesarethecivilliberties
ADA scoresfortheSenateandpresident
arerelevant
andextendfarther
backintimethando otherissue-specific
scores.
To measurethemedianpositionoftheCourt,we look at themedian
term.
We compute
fromtheCourt'sprevious
votingscoreon civilliberties
ofthe
members
thisbylookingatthevotingscoresoftheeightcontinuing
oftheinterval
Courtandusingthemidpoint
[J4,J5]as themedian.Forexto filltheseatvacatedby
ample,in 1994 StephenBreyerwas nominated
Oftheeightjusticesfromthe1993term
theretirement
ofHarryBlackmun.
whowereretaining
theirseats,JusticeO'Connorhad thefourth
highest
thefifth.
Sincetheirscoreswere36.2and
Kennedy
votingscoreandJustice
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SUPREME COURT NOMINATIONS
1081
44.7,respectively,
themedianwe use forBreyer's
appointment
is 40.5,the
averageofthesetwoscores.17
5. EMPIRICAL ANALYSIS
Table2 presents
thedistribution
ofnominations
byregimetype.Ofthe
twenty-eight
observations,
themajority-eighteen,
tobe specific-fallinto
Regime1. Threenominations
(Stevens,Bork,andKennedy)fallintoRegime2. Theremaining
sevennominations
belongto Regime3. The existineachregime
willallowus fullytotestourtheory,
enceofnominations
but
ofobservations
in thesecondandthird
thesmallnumber
regimeswilldeofobtaining
creasethelikelihood
statistically
significant
results.
As ourtheoretical
modelindicates,thelocationof thenominee,N,
ofthepresident's
shouldbe a function
idealpoint,theSenate'sindifference
point,andtheexisting
medianon theCourtoncea vacancyoccurs.Howwhichofthesevariables
shouldhavean
ever,thetypeofregimedetermines
effect
onN. InRegime1 we expectP tohavea significant
effect;
inRegime
2 we expectIs tohavea significant
effect;
andin Regime3 we expectJto
havea significant
effect.
Bivariate
analysisprovides
initialsupport
forourmodel.In Regime1,
between
thepresident's
thereis a strong
relationship
ideologyandthenomiinRegime3,we finda strong
nee'sideology(r= .60,p < .01).Similarly,
relationship
between
theCourtmedianandthenominee's
ideology(r= .76,p
< .05).In Regime2 we do notfindsupport
forourtheory
(r= -0.08); thisis
ofobservations
inthisregime.
unsurprising,
giventhesmallnumber
Column1 in
Table3 presents
theresultsofourswitching
regressions.
themostbasicandstraightforward
testofourmodel.All
thistablepresents
Both
threeofthevariables
havepositive
as thetheory
coefficients,
predicts.
thepresident's
ideologyin Regime1 andtheCourt'smedianin Regime3
differ
fromzeroatp < .01.18OnlytheSenate'sindifference
pointinRegime
2 failstoreachstandard
hereandina range
levelsofsignificance,
although
On the
ofotherspecifications
itscoefficient
is in theexpecteddirection.
theideologyofnominees
to
whole,themodeldoesa goodjob ofpredicting
theCourt.
andspecifitoa discussion
ofalternative
Beforeproceeding
hypotheses
cations,we wishto maketwogeneralpointsaboutourempirical
analysis.
members
on theCourtwhena nomineewas
'7insomecases,therewereonlysevencontinuing
justice.In othercases,there
chosen.In suchcases we use thevotingscoreofthemedian,orfourth,
butwhohad notyetestabweresevensitting
justicesandalso onejusticewhohadbeenconfirmed
juslisheda votingrecordon theCourt.Forthesecases we usedthevotingscoresofthecontinuing
justice.
ticealongwiththepredicted
voteofthenewlyconfirmed
are based on onelevelswe reportforthetheoretical
variablesof interest
18All significance
tailedtests.
BryonJ.Moraskiand CharlesR. Shipan
1082
Table2. NomineesClassifiedbyRegimeType
Regime1:
Unconstrained
President
Warren
Brennan
Whittaker
Stewart
White
Goldberg
Marshall
Burger
Haynsworth
Carswell
Blackmun
Powell
Rehnquist
(associate)
O'Connor
Rehnquist
(chiefjustice)
Scalia
Ginsburg
Breyer
Regime2:
Semi-Constrained
President
Stevens
Bork
Kennedy
Regime3:
FullyConstrained
President
Clark
Minton
Harlan
Fortas(associate)
Fortas(chiefjustice)
Souter
Thomas
andP <
Note:Regime1 occurswhenS < P < J;Regime
2 occurswhenP < S < J,S > (J4+ J)/2,
3 occurs
whenP < J< S. Thesameregimes
occurforthemirror-images
ofthese
2S - J;andRegime
as Regime
1).
preference
configurations
(i.e.,J< P < S alsois classified
proxiesforideology,
we reranthe
First,becauseADA scoresareimperfect
shownin Column1 (andotherspresented
in thispaper)using
regression
ADA scores
severalothermeasuresforideology.Usingraw(unadjusted)
thesameas-or in somecases,even
produced
results
thatwereessentially
than-thoseproduced
ADA scores.Adjusted
Wbetter
usingreal(adjusted)
support
forourtheory.
Becauseno
NOMINATEscoresalso yieldedstrong
is perfect,
measure
ofideology
arebetter
offusinga variety
ofmeascholars
surestotesta theory.
Thesimilarity
acrossdifferent
measures
inouranalytherobustness
sisdemonstrates
ofourresults.'9
ofourtheoretical
variables
canbe testedintwo
Second,thesignificance
ofthesevariables
different
ways.Ourtheory
predicts
thatthecoefficients
19TheNOMINATEscoreswererescaledfrom0 (conservative)
to 1 (liberal)so theywouldbe
consistent
withourothermeasures.Usingtheaverageofa president's
ideologyscoreoverthecourse
ofhistermproducedresultsthatwerenearlyidenticaltothosefoundin Column1. UsingthepresidentialideologyscoresofSegal,Howard,andHutz(1996), whicharebasedon expertassessments,
yieldedsimilarresults.
SUPREME COURT NOMINATIONS
1083
Table3. Predicting
theIdeologyofSupremeCourtNominees
Column 1
Column 2
Column 3
Column 4
0.83
(0.25)
Presidential
ADA Scores
(inRegime1 only)
0.83
(0.23)
0.87
(0.25)
0.92
(0.53)
Point
Senate'sIndifference
(inRegime2 only)
0.20
(0.32)
0.06
(0.30)
0.62
(0.39)
CourtMedian
(inRegime3 only)
1.18
(0.29)
1.42
(0.74)
1.23
(0.61)
Presidential
ADA Scores
(inRegimes2 and3)
-0.04
(0.42)
Point
Senate'sIndifference
(inRegimes1 and3)
-0.55
(0.30)
CourtMedian
(inRegimes1 and2)
0.18
(0.47)
ADA Scores
Presidential
(inallRegimes)
-0.04
(0.42)
Point
Senate'sIndifference
(inall Regimes)
-0.55
(0.30)
CourtMedian
(inall Regimes)
0.18
(0.47)
0.96
(0.29)
Constant
0.13
(0.10)
0.11
(0.25)
0.11
(0.25)
0.12
(0.10)
R2
Adjusted
0.41
0.49
0.49
0.31
SEE
0.26
0.24
0.24
0.28
Durbin-Watson
1.49
1.99
1.99
1.21
Numbers
inparentheses
arestandard
errors
N=28
shouldbe positive
andsignificantly
fromzero.In otherwords,our
different
modelpredicts
thatthesetheoretical
variablesshouldhavea positiveeffect
onthenominee's
ourtheory
ideology.
alsopredicts
thata one-unit
However,
variablesshouldproducea correspondchangeintherelevant
independent
ingone-unit
To testthissecondprediction,
changeinthedependent
variable.
is thatthecoefficient
is equalto one;andfailure
thepropernullhypothesis
torejectthisnullconstitutes
forourtheory.
areimBothpredictions
support
We cannotsimply
testwhether
fromone,bethecoefficient
differs
portant.
causea coefficient
fromonealso might
be indistinguishindistinguishable
able fromzero(e.g.,a coefficient
of 1.00 witha standard
errorof 2.00).
1084
BryonJ.Moraskiand CharlesR. Shipan
Similarly,we cannottestonlywhetherthecoefficient
differssignificantly
fromzero, since such a coefficientmightbe statisticallydistinguishable
fromone (e.g., a coefficient
of 0.20 and a standarderrorof 0.04). In theremainderof thepaper we will reportp-valuesbased on thenull hypothesis
thatthecoefficient
is equal to zero,butwe will also notewhetherthecoefficientsdiffersignificantly
fromone. It is extremely
important-andsupportive of ourtheory-tonotethatin everyinstancewherewe findthatthecoefficientsare significantly
different
fromzero, we also findthattheyare not
different
fromone.20
significantly
Alternative
Hypotheses
While themostbasic testof ourtheoreticalmodel is theone presented
in Column 1, ourtheoryalso producesadditionalhypotheses.In particular,
thetheorynotonlypredictsthatthepresident'sideologyshouldbe a significantinfluenceon thenominee'sideologyin Regime 1; it also predictsthat
thepresident'sideologyshouldnotbe a significant
influenceon thenominee's ideologyin Regimes2 and 3. Similarly,
theSenateshouldplay no role
in Regimes 1 and 3, and the Courtmedian should be insignificant
in Regimes 1 and 2. In otherwords,insteadof expectingthatthevariablesforthe
president,
Senate,and Courtshouldbe significant
and positive(and equal to
one) in all threeregimes,thetheorypredictsregime-specific
effects.The
equationto be estimatedis thus:
N=
P + PI
DI* P + P2* D2* IS + P3* D3* J+ P4* (D2+ D3) * P
+ 5 * (DI+ D3) * Is + 6 * (DI + D2) * J+ F
(2)
wherewe expectP, P, and 3 to be significant
and 4, P5, and P6 to be insignificant.
Column2 in Table 3 presentstheresultsforthealternative
specification
(2). Again,theresultsare supportive
of ourtheory.
The president'sideology
in Regime1,butnotin Regimes2 and 3, and theCourtmedian
is significant
in Regime3, butnotin Regimes1 and2. Bothvariablesalso are
is significant
fromone. Once again,theSenate'sindifference
indistinguishable
pointis not
a significant
influenceon ideologyin Regime2, althoughit curiouslyproduces a somewhatsignificant
butnegativecoefficient
forRegimes1 and 3.
Whilethisalternative
followsdirectlyfromourtheoretical
specification
model, a numberof otherhypothesesalso are plausible. For example,the
nominee'spositionmightbe a functionof thepreferences
of thepresident,
the Senate's indifference
point,and the Court,irrespectiveof theregime.
The expectationforthisalternative
hypothesis
wouldbe thatas theideologi20Wealso findthatourconstant
termis alwaysindistinguishable
fromzero,whichthetheory
also predicts.
SUPREME COURT NOMINATIONS
1085
cal scoresof anyof theseactorsincrease,so would theideologicalscoreof
thenominee.
we addedthesethreevariablesto Colhypothesis
To testthisalternative
umn 1 of Table 3 (i.e., we removedthe parentheticaltermsfromthe last
in Equation2). The resultsofthistest,shownin Column3,
threeinteractions
once again providesupportforour model. The president'sideologyin Rethatare
gime 1 and theCourt'smedianin Regime3 again have coefficients
fromzero atp < .05, and
different
are significantly
in thepredicteddirection,
fromone. Interestingly,
theSenate's indifference
are also indistinguishable
also approachesstandardlevels of significance(p
pointin thisspecification
fromone, lendingan additionalmeasureof
< .10) and is indistinguishable
supportto ourtheory.
At the same time,littlesupportis givento the alternativehypothesis.
in thepredicteddirection,
variablesare significant
None ofthenoninteracted
at the .05 level.21
and a joint F-testshowsthattheyarejointlyinsignificant
These results,like thosepresentedin theothercolumns,lend supportto our
As thetheory
theoreticalargumentand to therobustnessof our results.22
predicts,thepresident'schoice of a nomineeappearsto be a functionof the
pointin Rein Regime 1, the Senate's indifference
president'spreferences
gime2, and theCourt'smedianin Regime3.23
thattheseothervariablesareequal to one.As in
we can rejectthehypothesis
2'Furthermore,
pointwas weaklysignificant,
theSenate'sindifference
thepreviouscolumn,thevariablemeasuring
This impliesthat,forexample,ifP < Is < J,as Is movesto the
albeitwitha negativecoefficient.
forthisresult
no explanations
totheleft.We offer
willchoosea nomineefarther
thepresident
right,
research.
forfuture
an opportunity
butsimplynotethatitpresents
fromthe
theconstant
to varyacrossregimesbyomitting
22Similarly,
we allowedtheconstant
regimedummyvariandinsteadincluding
estimation
DI, D2, andD3. None ofthesenoninteracted
andtheinteracpreferences
ofD, withthepresident's
whiletheinteraction
ablesweresignificant,
at thep < .05 level.
tionofD3 withtheCourt'spositionremainedsignificant
Senthepresident,
thatwe tested:whether
hypotheses
twoofthealternative
23Thetextreports
inregimesinwhich
thesethreevariablesmatter
acrossall regimesandwhether
ate,andCourtmatter
one in
including
ofothernullhypotheses,
We also examineda variety
we expectthemnottomatter.
and Senatealone,one whereit is rewhichthenominee'sideologyis regressedon thepresident
and theSenate,one wherewe inand thedistancebetweenthepresident
gressedon thepresident
and
popularity
alone,andone wherewe includevariablesaboutthepresident's
cludethepresident
(discussedbelowwithrespecttoTable4).
in officeandthenominee'squalifications
timeremaining
variablesin thesemodels.Whilethereweresome
theoretical
We also includedtheregime-specific
interin generaltheresultsshowedthattheregime-specific
acrossthesespecifications,
differences
variableswerenot.The mainexceptiontothisocandthealternative
actiontermsweresignificant,
theoretical
in all threeregimeswiththethreeregime-specific
curredwhenwe includedthepresident
below.We
We discusscollinearity
was significant.
nothing
variables.In thiscase,duetocollinearity,
resultsfor
modelshad notgenerally
producedinsignificant
also notethatevenif thesealternative
resultsforvariableswe expectto be signifiand significant
variableswe expectto be insignificant
enoughto providespecific
arewell-developed
cant,it can be arguedthatnoneofthesealternatives
ortheoretical
interpretations.
alternative
hypotheses
1086
BryonJ.Moraskiand CharlesR. Shipan
Whiletheseresultssupport
ourtheory,
we wishto introduce
a bitof
cautionin interpreting
them.First,standard
is moreaphypothesis
testing
fortesting
a particular
whether
variableis significant
propriate
(i.e.,when
is thatthevariableis notdifferent
thenullhypothesis
fromzero)thanfor
wherethemodelholdsthata variableshouldbe insignificant.
situations
levelsofsignificance
Thus,conventional
shouldnotbe usedto determine
whether
thesecoefflcients
areindeedequaltozero,as thismight
resultina
Oneapproach
TypeII error.
thatsocialscientists
taketodealwiththisproblemis touse a morestringent
testofp < .50 fora one-tailed
test(e.g.,Hall
Grofman
Even
and
tothismuchmorestringent
1990).
according
test,none
ofthevariables
we expecttobe insignificant
in a
turnouttobe significant
positive
direction.
A secondproblemis moreseriousandhas to do withcollinearity
betweenthevariables.In bothColumns2 and3, collinearity
is a problem.24
twoofthestandard
Unfortunately,
waystofixcollinearity
arenotplausible
can
neither
options-we
addmoreobservations
nordeleteindependent
variables(Lewis-Beck1995).Thus,we cannotdirectly
addresstheproblem
of
collinearity.
Theprimary
effect
ofmulticollinearity,
ofcourse,is toincreasethesize
ofstandard
errors.
a biasagainst
Thus,itprovides
finding
significant
results.
We cannotknowwhether
areindistinguishable
coefficients
fromzerobecausethemodelis correct
orbecauseofmulticollinearity
andrandom
variationproducing
itis evenmoresurprising
spurious
results.
thatour
Therefore,
theoretical
inRegime1 andtheCourtmevariables-thepresident
primary
in
dian Regime3-remainsignificant
undera widerangeofspecifications.
In addition,
thesevariablesremainsignificant
foralternative
measures
for
eachvariable,
as notedearlier.
thevariables
thatwe do notexpect
Moreover,
tobe significant
alsoturn
outtobe insignificant
undera widerangeofspecifications
andoperationalizations.25
we cannotignoretheproblems
Although
24Forexample,thebivariate
correlations
rangefrom.01 to .89.Andwhenwe regressPresidentialIdeology(in Regimes2 and 3) on theotherindependent
variablesin Column2, we finda high
adjustedR2 (0.83). Otherdiagnostictestsweremuchmoreencouraging.
In Columns2 and 3 the
Durbin-Watson
statistic
allowedus to rejectthepossibility
ofautocorrelation
(in Column1 thestatisticis inconclusive).
thestandardized
residualsofColumn1 againstitsstanFurthermore,
plotting
dardizedpredicted
valuesdemonstrates
thattheanalysiswas notdrivenbyoutliers.
To complement
ofthedata,we reliedon Cook's distancetest,whichis a measureofhowmuch
thisvisualinspection
theresidualsofall cases wouldchangeifa particular
case wereexcludedfromthecalculationofthe
regression
coefficients.
A largeCook's D indicatesthatexcludinga case fromcomputation
oftheregressionstatisticschangesthecoefficients
In thecase of onlyone observationsubstantially.
StephenBreyer-didthistestindicatetheexistence
ofa potential
outlier.
Removing
Breyerfromthe
datasetactuallyimproved
ourresults-itincreasedtheoverallfitof themodeland madeourtheoreticalvariablesmoresignificant.
thedegreesof collinearity
25Comparing
ourtheoretical
variablesencounter
to thedegreesof
encountered
thealternate
collinearity
bythevariablesrepresenting
hypotheses
yieldsfurther
support
SUPREME COURT NOMINATIONS
1087
potentially
causedbymulticollinearity,
thestability
ofourresultsacrossa
widerangeoftestslendsadditional
support
toourfindings.
be interpreted?
Wewillnotbe surIn theend,howshouldthefindings
prisediffuture
theoretical
workdemonstrates
a moreimportant
roleforthe
in otherregimes.Becauseofthecollinearity
president
betweenthepresiitis difficult
toreject
dentialvariableandtheothervariables,
conclusively
thispossibility.
Andinthenextsectionwe explorea couplewaysinwhich
in Regimes2 and3. At
thepresident
mightbe able tobe moreinfluential
in
thispoint,however,
theevidencesuggests
thatthepresident
is significant
in Regime3, whilethese
Regime1, andtheCourtmedianis significant
inotherregimes.
variables
andtheSenatearenotsignificant
BorderlineObservations
Reclassifying
fromthepreviouscolumnsthathas notbeenconsistent
One finding
oftheSenate'sindifference
withourtheory
is thelackofsignificance
point
in Regime2. No doubtthisis due,at leastin part,to thesmallnumber
of
italso callsfora closerexamination
ofthe
casesin thisregime.However,
threeobservations
Anditturns
outthatinall three
thatoccurinthisregime.
be reclassified
as belonging
toone
casestheobservations
might
justifiably
oftheother
regimes.26
ofJohn
PaulStevensin 1975.Atthat
letus lookatthenomination
First,
ADA scorewas 18,theCourt'smedianinthe
time,President
Ford'sadjusted
was51.1,andtheadjusted
ADA score
wakeofJustice
Douglas'sretirement
twoofthesevalues,the
fortheSenatemedianwas 50.2.Basedonthelatter
vote
Senate'sindifference
pointwasthus49.3.BecauseStevens'spredicted
was fairlyconservative
would
(38.0), Senateapprovalofhisnomination
haveledtoa newmedianof49.3.SincetheSenatefellinbetween
theexistingandthepotential
newCourtmedians(i.e.,JandJ*),we classified
this
toRegime2. However,
observation
as belonging
giventhatthenewmedian
andtheSenate'sindifference
pointareequal,andgiventhatP is lessthan
to
bothS andJ,we couldjustas wellhaveclassified
Stevensas belonging
ADA Scoresvariforourtheory.
Forexample,in Column3 ofTable3 theRegime1 * Presidential
on theother
degreeofcollinearity
(an adjustedR2of .87 whenregressed
able suffers
froma greater
whenwe use
Furthermore,
variables,yetit is significant.
variables)thananyof thenontheoretical
decreasesa greatdeal,yettheresultsremainthesame.
unadjusted
ADA scores,collinearity
to determine
which,if any,classifica26Wehastento add thatwe examinedall observations
borderOnlythoseclassifiedas belongingto Regime2 wereevenremotely
tionswereborderline.
classifiedas belongingto otherregimeswereclose to theregimeborders.
line-no observations
inordertoprovideposthoc exRegime2 observations
Thus,we stressthatwe arenotreclassifying
predicts
becausethetheory
oftheRegime2 variable.Rather,
planations
forthelackof significance
suchsharpcutpoints
andbecausethereareonlythreecases in thisregime,we believeitmakessense
to see howsecurelytheyfitintoRegime2.
toexaminethesecases individually
1088
BryonJ.Moraskiand CharlesR. Shipan
Regime 1.27More generally,anytimea nominationis thisclose to theborsincetheidederof two regimes,classificationof regimetypeis uncertain,
ology and votingscores shouldbe consideredto measuretruepreferences
on thepartof thepoliticalactors
withsome errorand since anyuncertainty
could lead to a changein regimeclassification.
similarlyshowsthat
ExaminationoftheBorkand Kennedynominations
In bothcases theSenatemedianis
thesealso could be classifieddifferently.
less than,butveryclose to, theCourtmedian,withS = 48.2 and J= 48.6,
respectively.Since thepresident'sideal pointis much less thaneitherof
theseotherpoints,we classifiedthesenominationsas belongingto Regime
2. However,because thevalues forS and Jare extremelyclose, bothBork
and Kennedycould veryplausiblybe reclassifiedas belongingto Regime3,
whichcalls forthepresidentand Senateto be on oppositesides of theCourt
median.28
we re-estimated
Based on thesereclassifications,
Equation1. In Column
4 of Table 3, Stevensis movedintoRegime 1 whileBork and Kennedyare
placed in Regime3. The resultsagain showsupportforourtheory.Boththe
Courtmedianin Regime3 and thepresident'sideologyin Regime 1 are sigfromone.29
nificantly
different
fromzero and indistinguishable
Controlling
for thePresident'sBargainingAdvantage
Severalotherfactorsoutsideof our model mightaffectthechoice of a
nominee.We would not,however,expectthesefactors,whichwe can think
underall condiof as thepresident'sbargainingadvantage,to be important
derivedindependent
variablesdiscussed
tions.Rather,like thetheoretically
earlier,we expectthatifthesevariablesmatter,
theydo so onlyin certainregimes.We offertheseas additionalalternativesto our model, alternatives
thatderivefromthedescriptiveand historicalworkon nominations.
in Regime 1 we wouldnotexpecttheseotherfactors
More specifically,
to matter,
whereaswe mightexpectthemto matterin Regimes2 and 3. In
Regime 1, thepresidentalreadycan nominatesomeonewho shareshis ideology.He cannotuse anypoliticalcapitalhe mighthave to move thenominee closerto his own position.In Regimes2 and 3, however,thepresident
mustchoose a nomineelocatedsome distancefromhis own mostpreferred
sincetheCourtmedianand theSenatemedianareseparatedby onlyone per27Furthermore,
centagepoint,itcouldalso be thecase thatJ< S, or atleastthatactorsperceivethatJ< S, in which
case thiscouldbe classifiedas belongingtoRegime3.
281naddition,
civillibertiesvotingscoresprobablyunderstate
theconservative
aggregate
natureoftheRehnquist
Court(Baum 1995;Lee, Sandstrum,
andWeisert1996).
29Wealso performed
a switching
regimesregression,
usingLIMDEP, on thisequation.This
procedure
similarly
yieldedsignificant
resultsforthesevariables.
SUPREME COURT NOMINATIONS
1089
point.30Several factorsmight,however,enable him to choose a nominee
suchthatP < N < Is (in Regime2) or P < N < J(in Regime3).31
We propose and testthreesuch variables: presidentialapproval,the
president'syear in office,and the qualificationsof the nominee.Each of
thesevariableswas recodedforplacementon theintervalfromzero to one.
The approvalratings,whichregisterthepercentageof people approvingof
the president,were acquired forthe monthof each nominationfromthe
Gallup Opinion Poll.32Gallup asked the same questionin each monthfor
each yearin oursample:"Do you approveor disapproveoftheway [thecurrentpresident]is handlinghis job as president?"The descriptiveliterature
themore
on nominationssuggeststhatthegreatera president'spopularity,
likelyhe is to be able to choose a nomineecloserto his ownideal point.
themorerecentlya presidenthas been elected,themoresucSimilarly,
cessfulhe shouldbe in bargainingwiththeSenate.Consequentlywe include
a variablemeasuringthepercentageof thepresident'stermthatremainsto
be served.This variabletakeson thevalue of 1 in thepresident'sfirstyearin
office,0.75 in thesecondyear,and so on.
Finally,themorequalifieda nomineeis, theharderitwillbe fortheSenate to rejectheror him.Thus,a presidentwill be able to nominatesomeone
These qualification
who is closerto P if thatnomineeis highlyqualified.33
thevariablesdisvariables.By including
exampleofregime-specific
30Thuswe haveanother
we wouldbe biasingtheresultstoward
themwithspecificregimes,
cussedbelowwithout
interacting
(Regime1) withregimes
zero,sincewe wouldbe mixinga regimewherewe expecttofindno effect
whenwe didincludethebargaininwhichan effect
mightexist(Regimes2 and3). Notsurprisingly,
effects,
theresultswereinsignificant.
ingvariableswithout
regime-specific
if important,
shouldimprovea
modelit,thesefactors,
31In effect,
whilewe do notformally
alreadycan nominate
gamewiththeSenate.Sincethepresident
president's
positionin a bargaining
he neednotbargain,
someonelocatedat hisidealpointwhenfacedwitha Regime1 configuration,
in thatregime.However,we shouldnotethatallowing
and thesefactorsshouldnotbe important
acrossall threeregimesdidnotaltertheresultsshownbelow.
thesevariablestomatter
ofKennedyin November1987.
32Galluplackeddataon Reaganat thetimeofhisnomination
As a result,we usedhis approvalratingforthelastmonththeyhad it available,whichwasAugust
1980,Report
1987. RatingswereobtainedfromThe Gallup OpinionIndex,October-November
Number182 andTheGallupPoll: PublicOpinion,1981-1995.
If,forexample,P < Jin
33Allvalueswererescaledto accountforthelocationofthepresident.
to decreasethevalue of N, whereasif
Regime3, thenwe wouldexpectan increasein popularity
to increasethevalueofN. Because theexP > J,thenwe wouldexpectan increasein popularity
is inapproaccordingto whether
P is to theleftorto therightofJ,D2*Approval
pectedsignsdiffer
thisinteraction
issueis tomultiply
waytocorrect
forthedirectional
priate.Themoststraightforward
termby thedifference
betweenP and theCourt(forRegime3) or P and theSenate'sindifference
point(forRegime2). For example,forpopularitythemeasuresare D2*Approval*(P- Is) and
butalso forthedistancebetweenthe
D3*Approval*(P- J).This controlsfornotonlydirection,
president's
ideal pointand theotherpoints.Equivalentchangesweremadefortheothervariables.
that,forexample,a verypopuWe controlfordistanceas wellas direction
becausewe hypothesized
changein thenominee'sposition
larpresident
in Regime3 locatedfarfromJcouldlead to a greater
1090
Bryon
J.Moraski
andCharles
R.Shipan
scoreswereobtainedfromThe SupremeCourtCompendium(Epsteinet al.
1996) and werecomputedin thesamewayas theSegal/Cover
ideology
scores.
Theresultspresented
inTable4 demonstrate
littlesystematic
support
forthesefactors.34
It appearsthatinRegime3 thereis atleastsomereason
intheexpected
tobelievethatthesevariables
affect
thechoiceofa nominee
manner.
Highapproval
ratings,
proximity
to an election,
anda morehighly
qualifiednomineeall seemto allowa president
in Regime3 to nominate
someonewhosepredicted
voteis onthepresident's
sideoftheCourt'smedian.However,
eveninthisregime
theresults
arenotstrong:
withone-tailed
teststhep-valuesrangefrom.07 forapprovalandqualifications
to .15 for
in
yearsremaining office.
Twofinalpointsareimportant
tonotehere.First,we do notdoubtthat
thesefactors
sometimes
matter.
Whatwe showhereis thattheyarenotsystematic,
regular,
andsignificant
on thepresident's
choice.Secinfluences
be calledtheelecond,the"YearsRemaining"
variable
tapsintowhatmight
toralcontext,
whereasmostofthispaperhasbeendevoted
tolookingatthe
institutional
context.
Theseresults,
as wellas otherunreported
results,
providelittleevidenceofa significant
influence
from
theelectoral
context.35
AdditionalInterpretations
Whatadditional
canbe drawnfromourresubstantive
interpretations
sults,particularly
thosefoundinColumns1,2, and3 ofTable3? First,the
modelmakesitclearthatpresidents
arefacedwithdifferent
constraints
at
different
times.Twoofthefirst
three
justicesthatRonaldReagannominated
wereextreme
conservatives
(WilliamRehnquist
andAntonin
Scalia).Yethis
finalnomineetothebenchwas therelatively
moderate
Anthony
Kennedy.
One difference
betwee-n
thesecontexts
was theregime.ForReagan'sfirst
threeappointments,
he was unconstrained
(i.e.,Regime1). His partycontrolled
theSenate,andhewasabletochooseanynominee
hewished,
knowthana verypopularpresidentlocateda veryshortdistancefromJ.We also triedusinga signed
dummyvariable(e.g.,insteadof (P - J)we used-1 ifJ> P and 1 ifP > J).Thisproducedno substantive
differences
in theresults.
34Becauseofcollinearity
andlimiteddegreesoffreedom,
we havechosentoreport
thesevariables separatelyratherthantogether.
Whenwe includeall thevariablesshownin Table 4 in one
equation,theonlyvariablesthataresignificant
arepresidential
ideologyin Regime1 andtheCourt
medianinRegime3.
35Wealso examinedwhether
thechoiceof a nomineewas affected
by a hostof otherrelated
variables,suchas whether
it was a president's
forre-election,
firstterm,whether
he was running
whether
he was in hislastyearin office,
whether
he was in hislasttwoyearsin office,andwhether
he was an unelected
president
(i.e.,Johnson
andFord).Noneofthesevariablesweresignificant.
Nor
werevariablescontrolling
forthenumberofpreviousnomineesor appointments.
SUPREME COURT NOMINATIONS
1091
Table4. Controlling
forAdditionalFactorsin theNomination
ofSupremeCourtJustices
Column 1
Theoretical
Variables
Presidential
ADA Scores(inRegime1)
Column 2
Column 3
0.80
(0.23)
0.81
(0.24)
0.78
(0.23)
Senate'sIndifference
Point(inRegime2)
0.30
(1.10)
0.74
(4.53)
-0.06
(1.61)
CourtMedian(inRegime3)
1.04
(0.30)
1.06
(0.32)
0.95
(0.33)
Additional
Factors
Presidential
Approval
(inRegime2)
Presidential
Approval
(inRegime3)
0.27
(2.23)
0.91
(0.59)
YearsRemaining
inOffice(inRegime2)
0.10
(8.50)
YearsRemaining
inOffice(inRegime3)
0.53
(0.51)
Nominee's
Qualifications
(inRegime2)
-0.25
(1.86)
Nominee'sQualifications
(inRegime3)
1.00
(0.65)
Constant
0.14
0.13
0.15
(0.10)
(0.10)
(0.10)
R2
Adjusted
0.41
0.38
0.41
SEE
0.26
0.26
0.26
Durbin-Watson
1.54
1.51
1.59
Numbers
inparentheses
arestandard
errors
N =28
after
ingthattheSenatewouldbe likelytoapproveofhimorher.However,
the1986
theSenatechangedhandsandwas controlled
after
byDemocrats
OnceinRegime3, he
situation.
election,
Reaganwasfacedwitha different
wasconanextreme
butrather
wasnolongerabletonominate
conservative,
strained
becausetheSenate'spreferred
pointwas on theothersideofthe
Courtmedian.
Bill Clinton,
on theotherhand,disappointed
someDemocrats
bynot
choosingjusticeswhoweremoreliberal.Andindeed,StephenBreyer's
1092
BryonJ.Moraskiand CharlesR. Shipan
prenominationrecordwas perceivedto be fairlymoderate.On the other
hand,RuthBader Ginsburg'sSegal/Coverscoreis liberal,and evenBreyer's
scorewas farmoreliberalthanall butone ofthenomineesfromtheprevious
twenty-five
years.Interestingly,
shortlyafterBreyerwas approved,Clinton's
partylostcontroloftheSenate.This changedthepoliticalcontextto Regime
3, whichwouldfurther
constrainClinton'sabilityto nominatea moreliberal
jurist.
The model also allows us to speculateon the substantiveinfluenceof
regimesand of elections.If George Bush had defeatedBill Clintonin the
1992 election,Bush certainlywouldhave chosennomineeswho weremore
thanGinsburgand Breyer.But at thesame time,thenomination
conservative
contextinsteadwould have been Regime 3, compellingBush to choose a
moderatenomineeratherthana strongly
conservative
nominee.Speculating
evenfurther,
ifBush had been in officewhentheRepublicansgainedcontrol
of the Senate in 1994, we would have switchedback to Regime 1, where
Bush wouldhavebeen unconstrained.
In thissituationa justicelikeWilliam
Rehnquistmighthaverealizedthatconditionswereripefora successorwho
sharedhis ideology and thatit mightbe a strategically
opportunetimeto
retire.
6. DiscUSSION
Presidents view Supreme Court nominationsas importantpolicy
choices. To help ensureSenate approvalof theirnomineesand to move the
theymust
policy orientationof the Courtcloser to theirown preferences,
takeintoaccountthepreferences
of theSenateand theideologyand behavior of continuingmembersof the Court.Our theoreticalmodel, whichis
supportedby our empiricalresults,spells out theway in whichpresidents
engagein such strategic
behavior.
One potentialextensionto ouranalysiswouldbe to incorporate
theSenate JudiciaryCommittee,whichholds hearingson each nominee,intothe
theoreticalmodel. Includingthiscommitteewould change thepresident's
calculus.No longercould he worryaboutonlytheSenatemedian;he would
also have to worryaboutthecommitteemedian.36However,whiletheJudirole in theconfirmation
ciaryCommitteeundoubtedlyplays an important
process,and whilethepresidentundoubtedly
takesintoaccountthepreferences ofitsmembers,thecommittee
Even ifthe
does not act as a gatekeeper.
committee
disapprovesofa nominee,it stillcan sendthatnominee'snameto
the floorfora vote by the entireSenate.37For example,neitherClarence
36SeeNokkenandSala (Forthcoming)
forsucha model.
371fthecommittee
approvesa nominee,it automatically
sendsthenomination
to thefloor.If
thecommittee
doesnotapprovethenominee,
itcan choosewhether
ornottosendthenomination
to
thefloor.
SUPREME COURT NOMINATIONS
1093
Thomas norRobertBork won a majorityof thevote withinthecommittee,
to thefloor.
of bothof thesemenwereforwarded
yetthenominations
Instead of actingas a gatekeeper,the committee'sprimaryrole is to
thatsendsa signalto therestoftheSenate.Whether
makea recommendation
the committeeacts as a bindingconstraintand absolutelyneeds to be inan open question.On theone hand,the
cluded in thisanalysisis therefore
Senatehas neverapproveda nomineewho was voteddownby thecommittee,withThomas'scommitteevoteof 7-7 beingtheonlynearexception.On
theotherhand,thecommitteedoes notgatekeep;thus,its functionis probtransmission.
ablybetterhandledby a modelofinformation
Second,ourpaperwas motivatedby theobservationthatin thiscentury
presidentshave been enormouslysuccessfulin gettingtheirnomineespast
theSenate. However,it is worthnotingthatfailednominationswere more
commonin thenineteenthcentury,as were closely contestedvotes.Were
in thenineteenth
cenin generalmorecontentious
appointments
presidential
turythanin thiscentury?Did presidentstreatSupremeCourtappointments
While such questionsare beyondthescope of thisstudy,they
differently?
are certainlyworthyof attention.Our analysisrepresentsa buildingblock
butwe acknowlofpresidential
appointments,
towarda fullerunderstanding
edge thatfutureresearchshould attemptto deal withtheseothersortsof
questions.
Third,instead of using the median voterof the Senate, futurework
pivot.
mightconsiderusingthememberoftheSenatelocatedat thefilibuster
on a nominaThe reasonforthis,of course,is thattheSenatecan filibuster
tion,a tacticthatthepresidentwill need to takeintoaccount.While theuse
is a rareevent,itsinfrequency
on a SupremeCourtnomination
ofa filibuster
does notdenoteitsunimportance.38
Fourth,we believe scholarsshould proceed cautiouslywhen moving
fromour model to anypredictionsaboutSenate voting.Even leavingaside
has madean errorwhenchoosinga nominee
thepossibilitythatthepresident
(whichpresidentssurelyhave done),we wouldnotexpectall Senateconfirwhichthisanalysismightseem to
mationvotesto consistofbaremajorities,
andtheconindicate.Eventsthathappenbetweenthepresident'snomination
firmation
votecan influencetheSenate's action.In thecases of Fortasand
madepublicsubsequenttothenomination
Thomas,forexample,information
but priorto the confirmation
vote undoubtedlyshiftedthe votes of some
members.In addition,individualsenatorsmightbe influenced
bypartyleadakinto a snowballeffect,
causinga largerthan
ers,norms,orevensomething
expectedmajorityto votefora nominee.Thus,we recognizethattheSenate
afteritwas
ofAbe Fortastothepositionofchiefjusticewas withdrawn
38The1968nomination
conceivablethatBill Clintonhad thefilibuster
filibustered
in theSenate.In addition,it is entirely
moderateStephenBreyertothebench.
pivot(Krehbiel1998) in mindwhenhe nominated
1094
BryonJ.Moraskiand CharlesR. Shipan
mightpay attention
to factorsotherthanpolicypositionswhenvotingon SusuchfactorsintofupremeCourtnomineesand recognizethatincorporating
models
make
for
a
richer
ture
might
analysis.
model
While theseand otherchangesmightbe made to our theoretical
we
believe
our
new
on
and empiricaltests,
that
light the
analysis sheds
nominations
process.Thereis a reasonmostSupremeCourtnomineeseasily pass theSenate: presidentsact strategically
to choose thebest nominee
thattheyface.
theycan, giventheconstraints
March16, 1998.
Manuscriptsubmitted
Final manuscript
receivedMarch8, 1999.
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