R.I. Gen. Laws § 45-21-47
The right to amend, alter, or repeal this chapter at any time or from time to time is expressly reserved, and in that event the liability of the municipal employees' retirement system is limited in the case of a member or a person claiming through the member to the contributions made by the member, without interest, and in the case of a municipality, to contributions made by the municipality without interest, subject to deductions prescribed in the case of withdrawal by a municipality as provided in § 45-21-6. All retirement allowances or other benefits granted by the retirement of members, and in force prior to a repeal or amendment, are vested in the beneficiaries of the retirement allowances and shall be paid in full in accordance with the terms of this chapter, and the rights of the retirement board to compel the payment by any municipality of the sum or sums necessary to provide the retirement allowances granted to members formerly employed by the municipality shall not be affected by the repeal or amendment.
R.I. Gen. Laws § 45-21-47