Sec. 27. CERTAIN WRITTEN AGREEMENTS BETWEEN PENSION SYSTEM AND CITY AUTHORIZED. (a) Notwithstanding any law to the contrary, the board or a designee of the board is responsible for representing the interests of the pension system and all pension issues and benefits affecting the pension system or its members and beneficiaries under this article. The board may enter into a written agreement with the city on behalf of the pension system and members and beneficiaries of the pension system if the agreement is approved by the board and signed by the mayor and the board or the board's designee.

(b) A pension benefit or allowance provided by this article may be increased if the increase:

(1) is first approved by a qualified actuary selected by the board;

(2) is approved by the board and the city in a written agreement as authorized by this section; and

(3) does not deprive a member, without the member's written consent, of a right to receive benefits when the member is fully eligible.

(c) In a written agreement entered into between the city and the board under this section, the parties may not:

(1) alter Sections 9 through 9E of this article, except and only to the extent necessary to comply with federal law;

(2) increase the assumed rate of return to more than seven percent per year;

(3) extend the amortization period of a liability layer to more than 30 years from the first day of the fiscal year beginning 12 months after the date of the risk sharing valuation study in which the liability layer is first recognized; or

(4) allow a city contribution rate in any year that is less than or greater than the city contribution rate required under Section 9D or 9E of this article, as applicable.