Despite any delegation clause, a court must always determine whether the parties entered into an arbitration agreement as well as rule on any challenge to the delegation clause specifically. Here, the court found that the Chickasaw Nation had entered into an arbitration agreement with Caremark. The Chickasaw Nation did not automatically waive its sovereign immunity by agreeing to arbitration, but instead merely changed forums. The Nation’s argument that its contract with Caremark violated the Indian Health Care Improvement Act (25 U.S.C. § 1621e) challenged the Caremark agreement as a whole, not the delegation clause in particular and so had to be resolved by the arbitrator. Thus, the district court properly compelled arbitration, but no views were expressed on how the arbitrator should resolve the Nation’s claims of sovereign immunity or violation of section 1621e.