(2) A person may not receive benefits from more than one system for the same service, but the legislature may provide by law that a person with service covered by more than one system or program is entitled to a fractional benefit from each system or program based on service rendered under each system or program calculated as to amount upon the benefit formula used in that system or program. Transfer of service credit between the Employees Retirement System of Texas and the Teacher Retirement System of Texas also may be authorized by law.
(3) Each statewide benefit system must have a board of trustees to administer the system and to invest the funds of the system in such securities as the board may consider prudent investments. In making investments, a board shall exercise the judgment and care under the circumstances then prevailing that persons of ordinary prudence, discretion, and intelligence exercise in the management of their own affairs, not in regard to speculation, but in regard to the permanent disposition of their funds, considering the probable income therefrom as well as the probable safety of their capital. The legislature by law may further restrict the investment discretion of a board.
(4) General laws establishing retirement systems and optional retirement programs for public employees and officers in effect at the time of the adoption of this section remain in effect, subject to the general powers of the legislature established in this subsection.
(2) The legislature shall establish by law an Employees Retirement System of Texas to provide benefits for officers and employees of the state and such state-compensated officers and employees of appellate courts and judicial districts as may be included under the system by law.
(3) The amount contributed by a person participating in the Employees Retirement System of Texas or the Teacher Retirement System of Texas shall be established by the legislature but may not be less than six percent of current compensation. The amount contributed by the state may not be less than six percent nor more than 10 percent of the aggregate compensation paid to individuals participating in the system. In an emergency, as determined by the governor, the legislature may appropriate such additional sums as are actuarially determined to be required to fund benefits authorized by law.
(B) a statewide system of benefits for the officers and employees of counties or other political subdivisions of the state in which counties or other political subdivisions may voluntarily participate; and
(C) a statewide system of benefits for officers and employees of cities in which cities may voluntarily participate.
(2) General administration of the Judicial Retirement System of Texas is by the Board of Trustees of the Employees Retirement System of Texas under such regulations as may be provided by law.
(f) Retirement Systems Not Belonging to a Statewide System. The board of trustees of a system or program that provides retirement and related disability and death benefits for public officers and employees and that does not participate in a statewide public retirement system shall:
(2) hold the assets of the system or program for the exclusive purposes of providing benefits to participants and their beneficiaries and defraying reasonable expenses of administering the system or program; and
(3) select legal counsel and an actuary and adopt sound actuarial assumptions to be used by the system or program.


