法律英语考试LEC考试美国法根底知识SourcesoflawIntheUnitedStates，thelawisderivedfromfoursources.Thesefoursourcesareconstitutionallaw，statutorylaw，administrativeregulations，andthecommonlaw（whichincludescaselaw）。ThemostimportantsourceoflawistheUnitedStatesConstitution.Allotherlawfallsunder，andissubordinateto，thatdocument.NolawmaycontradicttheConstitution.Forexample，ifCongressenactsastatutethatconflictswiththeConstitution，theSupremeCourtmayfindthatlawunconstitutional，anddeclareitinvalid.Notably，astatutedoesnotdisappearautomaticallymerelybecauseithasbeenfoundunconstitutional；itmustbedeletedbyasubsequentstatute.Manyfederalandstatestatuteshaveremainedonthebooksfordecadesaftertheywereruledtobeunconstitutional.However，undertheprincipleofstaredecisis，nosensiblelowercourtwillenforceanunconstitutionalstatute，andanycourtthatdoessowillbereversedbytheSupremeCourt.Conversely，anycourtthatrefusestoenforceaconstitutionalstatute（wheresuchconstitutionalityhasbeenexpresslyestablishedinpriorcases）willriskreversalbytheSupremeCourt.