ANTINOMIESOFPUBLICANDPRIVATEATTHEFOUNDATIONSOFINTERNATIONALINVESTMENTLAWANDARBITRATIONAlexMills*ABSTRACTInternationalinvestmentlawhasinrecentyearsbecomeatopicofgreatpracticalandacademicimportance,asthethousandsofinternationalinvest-menttreatieshavegivenrisetohundredsofinvestor-statearbitrations,andinnumerablebooksandarticles.Butfundamentalquestionsconcerningtheregulatorycharacterofinternationalinvestmentlaw,andwhatitsaimsandobjectivesare,remainthesubjectofcontestationreflectedinavarietyofpolicydebatesandincompetinghistoricalnarrativesregardingthedevelop-mentofthefield.Thisarticlecontendsthattwo‘public–private’distinctionsorantinomiesliebehindthisindeterminacy,atinternationalinvestmentlaw’suncertainfoun-dations—thefirstdealingwiththecharacterizationofinternationalinvest-mentlawasaformof‘public’or‘private’law,andtheseconddealingwiththebalancethatinternationalinvestmentlawstrikesbetween‘public’and‘private’interestsorobjectives.Anumberofdisputedissuesininterna-tionalinvestmentlawandarbitration,whicharepresentedatthesurfaceasmerelytechnicalproblems,mayinreality,itisargued,beproductsofthesedeeperunderlyingtheoreticaluncertainties.*SlaughterandMayLecturerinLaw,SelwynCollege,UniversityofCambridge(alexmills@cantab.net).ThisarticlebenefitedfromthewarmhospitalityandgeneroussupportofanInternationalVisitingResearchFellowshipattheUniversityofSydney,andfromcommentsmadebyparticipantsintheInternationalInvestmentTreatyLawandArbitrationConference:EvolutionandRevolutioninSubstanceandProcedure,February2010,SydneyLawSchool,UniversityofSydney,andtheSocietyofInternationalEconomicLawBiennialGlobalConference,July2010,UniversityofBarcelona,andfromtheinsightfulcommentsoftwoan-onymousreferees.Allarbitralawardscitedtointhisarticlearepubliclyavailableate.g.(2),469–503doi:10.1093/jiel/jgr020.JournalofInternationalEconomicLawVol.14No.2OxfordUniversityPress2011,allrightsreservedatWuhanUniversityLibraryonMarch2,2012‘regime’ofinter-nationalinvestmentlaw?3Oraretherejustnumerousindividualinternationalinvestmentagreements?Isinternationalinvestmentlawaboutempoweringstates,amechanismforthemtopromotetheireconomicdevelopmentandadministrativesophistication?Orisitaboutdiscipliningthem,ameansofprotectinginvestors(andglobalizedmarkets)fromunfairregulatoryexcess?Fromoneperspective,internationalinvestmentlawisaspecializedsubjectofinternationallaw—anevolvingcombinationoftreaties,customaryinterna-tionallawstandards,andgeneralprinciples,strivingfor(andperhapsachiev-ing)universality.Fromanotherperspective,itisaspecializedsubjectofinternationalcommercialarbitration—aseriesofindividualbusinessdisputesbasedonparticular,usuallybilateral,treatyarrangements(andoftenalsooncontractsbetweeninvestorsandstatesgovernedbynationallaw),resolvedbyarbitraltribunals.Oneofthemoststrikingfeaturesofinternationalinvest-mentlawisthatallthesewaysofviewingthesubjectseemtobeatleastpartlytrue,andyetatthesametimetheyseemtocontradicteachother.1Seee.g.UnitedNationsConferenceonTradeandDevelopment,‘RecentDevelopmentsinInternationalInvestmentAgreements(2008–June2009),IIAMonitorNo.3(2009)’,UNCTAD/WEB/DIAE/IA/2009/8,at2(noting2,676knowninternationalinvestmentagreements).2Seee.g.UnitedNationsConferenceonTradeandDevelopment,‘LatestDevelopmentsinInvestor–StateDisputeSettlement,IIAIssuesNoteNo.1(2011)’,UNCTAD/WEB/DIAE/IA/2011/3,at1(noting390knowninternationalinvestmentarbitrations).3Seee.g.Jose´EnriqueAlvarezandKarlP.Sauvant(eds),‘TheEvolvingInternationalInvestmentRegime’(Oxford:OxfordUniversityPress,2011);JeswaldW.Salacuse,‘TheEmergingGlobalRegimeforInvestment’(2010)51HarvardInternationalLawJournal427;StephanW.Schill,TheMultilateralizationofInternationalInvestmentLaw(Cambridge:CambridgeUniversityPress,2009),369ff.470JournalofInternationalEconomicLaw(JIEL)14(2)atWuhanUniversityLibraryonMarch2,2012‘public–private’distinctionsliebehindthisindeterminacy,atinternation