Does a vested contractual right to earn a pension become vested contractual rights of the employee?

That, upon accepting public employment, an employee obtains a vested contractual right to earn a pension does not mean that all terms governing the pension system then in effect become vested contractual rights of the employee. "[A]n employee may acquire a vested contractual right to a pension but . . . this right is not rigidly fixed by the specific terms of the legislation in effect during any particular period in which he serves. The statutory language is subject to the implied qualification that the governing body may make modifications and changes in the system. The employee does not have a right to any fixed or definite benefits, but only to a substantial or reasonable pension. There is no inconsistency therefore in holding that he has a vested right to a pension but that the amount, terms and conditions of the benefits may be altered."¹⁷ (Kern v. City of Long Beach (1947) 29 Cal.2d 848, 855.)