Citizen Band Patawatomi Indian Tribe, 121 S. Ct … exactly who must sign an agreement to effectuate a waiver of sovereign immunity (usually the tribal council or tribal chairman) and stating that any …Citizen Band Patawatomi Indian Tribe, 121 S. Ct … exactly who must sign an agreement to effectuate a waiver of sovereign immunity (usually the tribal council or tribal chairman) and stating that any …