Ind. Code § 6-9-35-16
With respect to obligations of the capital improvement board described in section 12(a) of this chapter and bonds, leases, or other obligations for which a pledge has been made under section 14 of this chapter, the general assembly covenants with the holders of these obligations that:
(2) this chapter will not be amended in any manner that will change the purpose for which revenues from the tax imposed under this chapter may be used;
as long as the payment of any of those obligations is outstanding.
As added by P.L.214-2005, SEC.44.