Indiana Code Title 6. Taxation § 6-2.5-11-6

Sec. 6. No provision of the agreement authorized by this chapter in whole or in part invalidates or amends any provision of the law of Indiana.  Adoption of the agreement by the state of Indiana does not amend or modify any Indiana law.  Implementation of any condition of the agreement in Indiana, whether adopted before, at, or after membership of this state in the agreement, must be by the action of this state.