Wis. Stat. § 279.11: State pledge.

The state pledges to and agrees with the holders of bonds issued under this chapter, and with persons that enter into contracts with the authority under this chapter, that the state will not limit or alter the rights vested in the authority before the authority has fully met and discharged the bonds, including any interest due on the bonds, and has fully performed its contracts, unless adequate provision is made by law for the protection of the bondholders or persons entering into contracts with the authority.