In any suit instituted in the Supreme Court of the United States to determine the right of a State to what are commonly known as school lands within any Indian Reservation or any Indian cession where an Indian tribe claims any right to or interest in the lands in controversy, or in the disposition thereof by the United States, the right of such State may be fully tested and determined without making the Indian tribe, or any portion thereof, a party to the suit if the Secretary of the Interior is made a party thereto; and the duty of representing and defending the right or interest of the Indian tribe, or any portion thereof, in the matter shall devolve upon the Attorney General upon the request of such Secretary.