Sorry about the “quasi-banishment.” It’s a made up word, I know. :)
Mr. Mitchell contended that the Council’s action imposing certain restrictions on him (following a federal indictment charging him with fraudulent acts in connection with his position with a Nation gaming enterprise) subjected him to custody for purposes of ICRA, and sought habeas corpus relief. The Court held that Mr. Mitchell is not subject to custody or detention, and did not reach the question of exhausting tribal court remedies.
Here are the materials in Mitchell v. Seneca Nation of Indians (W.D. N.Y.):