(a) Any public retirement or pension system provided for by law in existence prior to January 1, 1985, may be changed by the General Assembly for any one or more of the following purposes:
(1) To redefine involuntary separation from employment; or
(2) To provide additional or revise existing limitations or restrictions on the right to qualify for a retirement benefit based on involuntary separation from employment.
(b) The General Assembly by law may define or redefine part-time service, including but not limited to service as a member of the General Assembly, for the purposes of any public retirement or pension system presently existing or created in the future and may limit or restrict the use of such part-time service as creditable service under any such retirement or pension system.
(c) Any law enacted by the General Assembly pursuant to subparagraph (a) or (b) of this Paragraph may affect persons who are members of public retirement or pension systems on January 1, 1985, and who became members at any time prior to that date.
(d) Any law enacted by the General Assembly pursuant to subparagraph (a) or (b) of this Paragraph shall not be subject to any law controlling legislative procedures for the consideration of retirement or pension bills, including, but not limited to, any limitations on the sessions of the General Assembly at which retirement or pension bills may be introduced.
(e) No public retirement or pension system created on or after January 1, 1985, shall grant any person whose retirement is based on involuntary separation from employment a retirement or pension benefit more favorable than the retirement or pension benefit granted to a person whose separation from employment is voluntary.