 Arguing for <unk> and Bayless was Jason W. Kellahin , for Amoco and Marathon Oil was John R. Cooney ( originally a separate case , but which was consolidated with this case ) , for the tribe was Robert J. Nordhaus , and on behalf of the tribe for the Solicitor General was Louis F. Claiborne . Kellahin argued that tribal sovereignty only extended to members of the tribe , citing both Oliphant and Montana v. United States , 450 U.S. 544 ( 1981 ) , both cases involving the jurisdiction of a tribal court over non @-@ Indians . Kellahin stated that those cases that allowed a tribe to tax non @-@ Indians were not due to tribal sovereignty , but were connected with the authority of the tribe to regulate who could enter the reservation , in the same manner as a landlord controlled their property . Cooney argued that the tax was a violation of the Commerce Clause , in that Congress divested the tribes of that authority when they enacted 25 U.S.C. § <unk> granting the states the right to impose a severance tax on reservation lands . Nordhaus , in arguing for the tribe , pointed out that there was first , no Congressional preemption of the tribal authority to tax , and that second , taxation was an inherent power of tribal sovereignty . Claiborne first distinguished Montana , noting that it dealt with non @-@ Indians on fee land owned by non @-@ Indians that happened to be within the boundaries of the reservation , something that was completely unrelated to the current case . 
