exxon eagerton argued february decided june alabama statute imposes severance tax oil gas extracted wells located state statute act enacted increased tax exempted royalty owners increase prohibited producers passing increase consumers appellant producers parties contracts provided allocation severance taxes among royalty owners nonworking interests contracts also required purchasers reimburse appellants severance taxes paid paying increase severance tax protest appellants producers filed suit alabama state seeking declaratory judgment act unconstitutional refund taxes paid concluding exemption prohibition violated equal protection clause fourteenth amendment contract clause prohibition also natural gas policy act ngpa trial held act invalid entirety ordered appellee alabama commissioner revenue refund taxes alabama reversed held prohibition act federal law insofar applied sales gas interstate commerce insofar applied sales gas intrastate commerce pp natural gas act enacted intended occupy field wholesale sales natural gas interstate commerce alabama prohibition trespassed upon authority federal energy regulatory commission ferc act regulate wholesale prices natural gas sold interstate commerce prohibition bars gas producers increasing prices pass particular expense increase severance tax purchasers whether producers permitted recover expense purchasers matter within sphere ferc regulatory authority pp although ngpa extended federal authority control natural gas prices intrastate market congress also provided extension deprive power establish price ceiling intrastate sales level lower federal ceiling since state may establish lower price ceiling may also impose severance tax forbid sellers pass customers pp exemption act violate contract clause since nullify contractual obligation appellants beneficiaries exemption provides incidence severance tax increase shall fall royalty owners nowhere producers may shift burden increase royalty owners pp prohibition act violate contract clause prohibition affected contractual obligations appellants beneficiaries constitute law impairing obligations contracts within meaning contract clause prohibition imposed generally applicable rule conduct main effect shield consumers burden tax increase effect existing contracts permitting producers pass increase consumers incidental cf producers transportation railroad california pp neither prohibition exemption act violates equal protection clause measures pass muster standard rationality applied considering equal protection challenges statutes regulating economic commercial matters prohibition plainly bore rational relationship state legitimate purpose protecting consumers excessive prices similarly alabama legislature reasonably determined exemption encourage investment oil gas production pp together exchange oil gas et al eagerton commissioner revenue alabama also appeal marshall delivered opinion unanimous rae crowe argued cause appellants briefs euel screws arendall argued cause appellants briefs louis braswell john breckenridge argued cause appellees cases briefs charles graddick herbert burson fn solicitor general lee elliott schulder david engels jerome feit filed brief et al amici curiae urging reversal justice marshall delivered opinion cases concern alabama statute increased severance tax oil gas extracted alabama wells exempted royalty owners tax increase prohibited producers passing increase purchasers appellants challenge prohibition exemption supremacy clause contract clause equal protection clause since alabama imposed severance tax oil gas extracted wells located state code et seq tax levied upon producers oil gas proportion ownership time severance shall paid person charge production operations person charge production operations authorized empowered required deduct amount due producers production time severance proportionate amount tax herein levied making payments producers statute defines producer ny person engaging continuing business oil gas production including owning controlling managing leasing oil gas property oil gas well producing manner oil gas receiving money valuable consideration royalty rental oil gas produced person royalty owner shall exempt payment increase taxes herein levied shall liable therefor acts amended code privilege tax herein levied shall absorbed paid persons engaged business producing severing oil gas producer shall pass costs tax payments either directly indirectly consumer express intent act tax herein levied shall borne exclusively producer severer oil gas acts appellants working interests producing oil gas wells located alabama drill operate wells responsible selling oil gas extracted appellants obligated pay landowners percentage sale proceeds royalties percentage depending upon provisions applicable lease within given production unit may tracts land owners land leased nonworking interests also entitled share sale proceeds appellants parties contracts providing allocation severance taxes among royalty owners nonworking interests proportion party share sale proceeds appellants also parties sale contracts required purchasers reimburse severance taxes oil gas sold paying increase severance tax protest appellants eight oil gas producers filed suit circuit montgomery county seeking declaratory judgment act unconstitutional refund taxes paid protest circuit ruled favor appellants concluding exemption prohibition violate equal protection clause contract clause prohibition also preempted natural gas policy act ngpa et seq supp although act contained severability clause held entire act invalid ordered appellee commissioner revenue state alabama refund taxes paid protest alabama reversed holding act valid entirety appellants appealed noted probable jurisdiction affirm part reverse part remand proceedings inconsistent opinion ii deal first appellants contention application prohibition gas federal law applicable principles recently summarized pacific gas electric state energy resources conservation development absent explicit language congress intent supersede state law altogether may found scheme federal regulation pervasive make reasonable inference congress left room supplement act congress may touch field federal interest dominant federal system assumed preclude enforcement state laws subject object sought obtained federal law character obligations imposed may reveal purpose fidelity federal savings loan assn de la cuesta quoting rice santa fe elevator even congress entirely displaced state regulation specific area state law extent actually conflicts federal law conflict arises compliance federal state regulations physical impossibility florida lime avocado growers paul state law stands obstacle accomplishment execution full purposes objectives congress hines davidowitz price first sale natural gas shall considered exceed maximum lawful price applicable first sale natural gas part first sale price exceeds maximum lawful price extent necessary recover state severance taxes attributable production natural gas borne seller although prohibition thus conflict ngpa nevertheless conclude federal law insofar applied sales gas interstate commerce extent prohibition represented attempt legislate field congress chosen occupy natural gas act gas act stat amended ed supp enacted provide federal power commission ferc authority regulate wholesale pricing natural gas flow interstate commerce wellhead delivery consumers maryland louisiana previously recognized phillips petroleum wisconsin frankfurter concurring gas act intended occupy field wholesale sales natural gas interstate commerce field previously left largely unregulated result absence federal action decisions striking state regulation sales natural gas interstate commerce committee reports bill became gas act clearly evidence intent ales resale wholesale sales interstate commerce example sales producing companies distributing companies considered local character even absence congressional action subject state regulation basic purpose present legislation occupy field held may act citations omitted emphasis added one fpc statutory duties determine reasonable rates sufficient permit company recover costs service reasonable return investment cost service therefore major focus inquiry normally included cost service proper allowance taxes reach different conclusion respect application prohibition sales gas intrastate commerce although ngpa extended federal authority control prices intrastate market supp congress also provided extension federal authority deprive power establish price ceiling intrastate producer sales gas level lower federal ceiling section ngpa stat set forth supp othing chapter shall affect authority state establish enforce maximum lawful price first sale natural gas produced state exceed applicable maximum lawful price subchapter chapter since state may establish lower price ceiling think may also impose severance tax forbid sellers pass purchasers sellers charging maximum price allowed federal law state tax increase coupled prohibition differ practical effect state tax increase coupled imposition state price ceiling maintains price ceiling imposed federal law prior tax increase cases sellers required absorb expenses might able pass customers absent state restrictions given absence express provision ngpa congress express approval one form state regulation think fairly inferred congress contemplated general scheme created ngpa preclude another form state regulation intrusive conclude prohibition federal law insofar applied sales gas interstate commerce insofar applied producer sales gas intrastate commerce iii turn next appellants contention exemption prohibition impaired obligations contracts violation contract clause appellants contract clause challenge exemption fails simple reason nothing suggest exemption nullified contractual obligations appellants beneficiaries relevant provision act ny person royalty owner shall exempt payment increase taxes levied shall liable therefor face portion act provides legal incidence tax increase fall royalty owners state look payment additional taxes contrast prohibition exemption nowhere producers may shift burden tax increase whole part royalty owners anything opinion suggest alabama interpreted exemption effect strain reach constitutional question speculating alabama courts might future interpret exemption forbid enforcement contractual arrangement shift burden tax increase see ashwander tva brandeis concurring unlike exemption prohibition restrict contractual obligations appellants beneficiaries appellants parties sale contracts permitted include prices increase severance taxes required pay oil gas sold contracts entered prohibition enacted terms extended period prohibition effect barring appellants passing tax increase purchasers prohibition nullified pro tanto purchasers contractual obligations reimburse appellants severance taxes prohibition thus affects contractual obligations appellants beneficiaries follow prohibition constituted law impairing obligations contracts within meaning contract clause see trust new jersey although language contract clause facially absolute prohibition must accommodated inherent police power state safeguard vital interests people energy reserves group kansas power light quoting home bldg loan assn blaisdell long recognized statute violate contract clause simply effect restricting even barring altogether performance duties created contracts entered prior enactment see allied structural steel spannaus law otherwise one able obtain immunity state regulation making private contractual arrangements trust new jersey supra contract clause deprive broad power adopt general regulatory measures without concerned private contracts impaired even destroyed result trust new jersey supra justice holmes put one whose rights subject state restriction remove power state making contract contract carry infirmity subject matter hudson mccarter thus state prohibition law may applied contracts sale beer valid entered beer massachusetts law barring lotteries may applied lottery tickets valid issued stone mississippi workmen compensation law may applied employers employees operating contracts employment made provision injuries new york central white like laws upheld cases prohibition prescribe rule limited effect contractual obligations remedies instead imposed generally applicable rule conduct designed advance broad societal interest allied structural steel supra protecting consumers excessive prices prohibition applied oil gas producers regardless whether happened parties sale contracts contained provision permitting pass tax increases purchasers effect prohibition existing contracts contain provision incidental main effect shielding consumers burden tax increase cf henderson thompson beer massachusetts supra prohibition imposed generally applicable rule conduct sharply distinguishable measures struck trust new jersey supra allied structural steel spannaus supra trust involved new york new jersey statutes whose sole effect repeal covenant two entered holders bonds issued port authority new york new jersey similarly statute issue allied structural steel directly adjust ed rights responsibilities contracting parties quoting trust new jersey supra statute required private employer contracted employees provide pension benefits pay additional benefits beyond agreed provide terminated pension plan closed minnesota office since statute applied employers entered pension agreements sole effect alter contractual duties cf worthen kavanaugh statute drastically limited remedies available mortgagees held invalid contract clause alabama power prohibit oil gas producers passing increase severance tax purchasers confirmed several decisions rejecting contract clause challenges state schemes displaced rates previously established contract midland realty kansas city power light held party contract utility invoke contract clause obtain immunity state public service commission imposition rate steam heating higher rate established contract declared state power annul supersede rates previously established contract utilities customers omitted union dry goods georgia public service rejected contract clause challenge order state commission setting rates charged supplying electric light power notwithstanding effect order contracts accord stephenson binford upholding law barred private contract carriers using highways unless charged rates might exceed contracted charge producers transportation railroad california particularly instructive present purposes case upheld order issued state commission newly enacted statute empowering commission set rates charged individuals corporations offering transport oil pipeline rejected contention pipeline owner statute override contracts contracts entered statute adopted order made material common carrier making contracts future transportation mortgaging property pledging income prevent postpone exertion state power regulate carrier rates practices contract clause constitution interpose obstacle exertion power iv finally reject appellants equal protection challenge prohibition exemption neither challenged provisions adversely affects fundamental interest see dunn blumstein shapiro thompson contains classification based upon suspect criterion see graham richardson mclaughlin florida need tested lenient standard rationality traditionally applied considering equal protection challenges regulation economic commercial matters see western southern life ins state board equalization minnesota clover leaf creamery kotch board river pilot standard statute sustained legislature reasonably concluded challenged classification promote legitimate state purpose see western southern life ins supra clover leaf creamery supra conclude measures issue pass muster standard prohibition plainly bore rational relationship state legitimate purpose protecting consumers excessive prices similarly think alabama legislature reasonably determined exemption encourage investment oil gas production conclusion respect exemption reinforced fact provision solely tax measure recently stated regan taxation representation washington egislatures especially broad latitude creating classifications distinctions tax statutes see lehnhausen lake shore auto parts allied stores ohio bowers foregoing reasons conclude application prohibition sales gas interstate commerce federal law uphold prohibition exemption appellants challenges contract clause equal protection clause since severability prohibition remainder amendments matter state law remand alabama determine whether partial invalidity prohibition entitles appellants refund taxes paid protest see supra accordingly judgment alabama affirmed part reversed part case remanded proceedings inconsistent opinion ordered footnotes appellants exxon gulf oil louisiana land exploration appellants exchange oil gas getty oil union oil california supremacy clause constitution provides constitution laws shall made pursuance thereof shall law land thing constitution laws state contrary notwithstanding art vi cl although appellants also contend application prohibition oil emergency petroleum allocation act epaa et seq ed supp regulations promulgated thereunder conclude jurisdiction consider contention decision discuss issue highest state failed pass upon federal question assumed omission due want proper presentation state courts unless aggrieved party affirmatively show contrary fuller oregon quoting street new york showing made although appellants represented trial held prohibition epaa juris statement examination trial opinion reveals fact made mention epaa anything record us indicate issue raised trial appellants address epaa brief alabama brief appellees exchange oil gas getty oil placid oil union oil california pp pass issue circumstances jurisdiction consider whether epaa application prohibition oil affirmatively appear issue decided bailey anderson general practice alabama appellate courts consider issues raised first time appeal see state newberry state graf burton burton civ app crews houston county dept pensions security civ app cert denied appellants also burdened labored argument denied due process alabama refusal consider legislative history amendments state severance tax history according appellants shows amendments intended apply certain wells located one county state apply statewide suffice say weight given legislative history alabama statute matter alabama law determined alabama see nowhere section ngpa stated oil companies entitled increases state severance taxes rather act merely provides lawful ceiling first sale wellhead may raised severance tax imposed two acts aimed entirely different purposes words although perfectly permissible oil gas companies raise price first sale natural gas subject limitations natural gas policy act act requires increase severance tax mandated act borne producer severer oil gas commissioner believes seller may include lawful maximum price amount equal alabama severance taxes borne seller resulting production natural gas commissioner believes intent alabama legislature adopting prohibition want perceived levying additional tax consumer therefore prohibited anyone passing along increase levied act tax brief appellee eagerton emphasis original although federal energy regulatory commission ferc amicus brief point statement conference report ceiling prices act exclusive state severance taxes borne seller conf see statement supports position prohibition conflict parties stipulated substantial portion gas extracted appellants sold interstate commerce app pp trial concluded prohibition conflict ngpa determine much taxes issue case levied gas sold intrastate interstate commerce remand alabama inquires question severability see infra holds alabama legislature intended impose tax increase severance gas increase passed consumers gas sold determination may made note cases involve attempt state prohibit gas producers passing cost factor production labor machinery prohibition might raise additional considerations present inducement create producers shift away factor production prohibition applied contract clause provides state shall pass law impairing obligation contracts art cl contracts appellants entered appear entitle reimbursement royalty owners share severance tax paid appellants proportion royalty owners interest oil gas regardless whether state law imposes tax producer royalty owner appellants cite following contractual provisions typical agreements contend impaired exemption lessor shall bear pay shall deducted royalties due hereunder lessor proportionate royalty share applicable severance production taxes levied imposed upon production leased premises app pp lessor lessee shall bear proportion respective participation production hereunder taxes levied minerals covered hereby part thereof severance production thereof increases taxes lease premises part thereof even contractual provisions interpreted entitle appellants reimbursement portion severance tax state law imposes royalty owners appellants still objection contract clause event increase severance tax absorbed appellants state nullified contractual obligation simply provisions interpreted impose obligation royalty owners reimburse appellants tax increase since appellants shown exemption affects anything legal incidence tax increase contention exemption gas act ngpa plainly without merit example appellant union oil party contract concerning oil purchaser required reimburse percent amount severance taxes paid seller excess rates taxes levied april ibid point aptly stated early decision holding statute prohibiting issuance notes unincorporated banking associations violate contract clause preventing performance existing contracts entered members associations said members formed contract dissolved stoppage business violation contracts prohibited constitution consider construction lead let us suppose one law gaming public masquerades companies formed purpose carrying practices suppose legislature state seriously convinced pernicious effect institutions venture interdict seriously contended constitution violated myers irwin serg rawle see generally home bldg loan assn blaisdell sutherland dissenting dillingham mclaughlin operation reasonable laws protection public headed making contracts reaching future holmes manigault springs parties entering contracts may estop legislature enacting laws intended public good ogden saunders wheat laws passed rendering unlawful even incidentally lawful time contract government puts end contract yet one ever imagined thereby violates obligation contract hale contract clause ii harv rev statutes review trust also implicated special concerns associated state impairment contractual obligations see energy reserves group kansas power light conclusion buttressed fact appellants operate industries subject heavy regulation see energy reserves group kansas power light supra price regulation existed foreseeable type law alter contract obligations veix sixth ward bldg loan purchased enterprise already regulated particular objects purchased subject legislation upon topic respect gas see supra energy reserves group kansas power light supra time prohibition effect federal government controlled prices crude oil epaa et seq ed supp regulations promulgated epaa established maximum prices categories crude oil cfr part subpart producers crude petroleum et seq appellants reliance barwise sheppard misplaced barwise owners royalty interests challenged texas statute imposed new tax oil production borne ratably interested parties including royalty interests statute authorized producers pay tax withhold royalty owners proportionate share tax royalty owners barwise parties contracts entitled specified shares oil produced lessee required lessee deliver oil free cost contended statute authorizing lessee deduct portion tax payments due impermissibly impaired lessee obligation deliver oil free cost concluded statute run afoul contract clause lease made subordination power state tax production oil apportion tax lessors lessee plainly stipulation lease avail power state impose tax prescribe shall duty state pay fix time mode payment true even though assumed admissible lessors lessee stipulate shall ultimately bear tax barwise relevant cases insofar confirms alabama power decide part legal incidence increase severance tax fall owners royalty interests see part supra