--ThebreachofcontractinFrenchlaw:betweensafetyofexpectationsandefficiencyPierreGarello∗Faculted’EconomieAppliquée,UniversitedeDroit,d’EconimieetdesSciencesd’Aix-Marseille,3AvenueRobertSchuman,Aix-en-Provence13628,FranceAccepted20August2002Introduction:whichpathwillleadustoabetterunderstandingofFrenchcontractlaw?Contractsaremarvelloustoolstohelpustoliveinaworldofuncertainty.Theyallowustoprojectourselvesintoanunknowablefuture,toinvest.LawyerswhohaveinspiredtheFrenchCivillawandcontributedtoitsevolution,aswellasmostlawyersintheworld,haveclearlyperceivedthenecessitytoprotectthatinstitution.“Thecontractis,asfarastheindividualisconcerned,thebestforecastinginstrumentgeneratinglegalsecurity,andthefavoredpathtofreedomandresponsibilitythatisnecessaryfortheflourishingofhumanbeingsinasociety.”1Contractsarefarfrommiraculoustools,however.Iftheymakelifeeasier,theydonotnecessarilymakelifeeasy.Asthefutureunfolds,oneorbothcontractingpartiesmaybetempted,orcompelled,tobreakhisorherpromise.But,themerefactthatthecontractisrunningintodifficultiesdoesnotforcethelawtodosomething!2Itisonlywhenoneofthepartiesdoesnotperformthatthelaw(thecourt,thelegislation),backedwithcoercivepower,hastogiveanopinion,todecidethecase.Inordertodososomeprinciples,ortheories,arerequiredtoreachajudgmentastowhatisthebestthingtodo.ThepresentstudyoftheFrenchcontractlawisbasedonthepremisethat,fromalawandeconomicspointofview,thereexistsbasicallytwopossiblewaystoaddressthisconcern:thefirstapproachrequiresthatwheneveraproblemarises,anassessmentbemadeofallcostsandbenefitsincurredbytheparties.Inotherwords,onemustattempttoevaluateinasufficientlyprecisewaytheconsequencesofthecourtdecision—oroftheruleoflawunderconsideration—forbothpartiesaswellasforthirdparties(includingpotentialfuturecontractors).Thelawthen—andmorepreciselyhere,contractlaw—shouldaimprimarilyatprovidingtherightincentivestocontractingparties,whereby“rightincentives”onemeansincentivestobehaveinsuchawaythatthedifferencebetweensocialbenefitsandsocialcostsb