Mass. Gen. Laws ch. 44A § 8
The commonwealth hereby covenants with the purchasers, holders and owners, from time to time, of qualified bonds that it will not repeal, revoke, rescind, modify, or amend the provisions of section seven so as to create any lien or charge on or pledge, assignment, diversion, withholding of payment, or other use of or deduction from any distributable aid or other amounts to be paid to any holder of qualified bonds which is prior in time or superior in right to the payment required by said section; provided, however, that nothing herein contained shall be deemed or construed to require the commonwealth to continue to make payments of distributable aid or other amounts or to limit or prohibit the commonwealth from repealing or amending any law heretofore or hereafter enacted for the payment or apportionment of such aid or other amounts, of the manner, time, or amount thereof.
Mass. Gen. Laws ch. 44A, § 8