In 2003, Thomas Carbonneau wrote that "freedom of contract . . . Is at the very core of how the law regulates arbitration," and he referred to this as "Contract's Empire." I think Carbonneau is right and that, if anything, arbitration law has moved even further since then in the direction of contract.
Hiro N. Aragaki, Arbitration: Creature of Contract, Pillar of Procedure, 8 Y.B. Arb. & Mediation 2 (2016).