Neb. Const. art. III, § 19

The Legislature shall never grant any extra compensation to any public officer, agent, or servant after the services have been rendered nor to any contractor after the contract has been entered into, except that retirement benefits of retired public officers and employees may be adjusted to reflect changes in the cost of living and wage levels that have occurred subsequent to the date of retirement.

The compensation of any public officer, including any officer whose compensation is fixed by the Legislature, shall not be increased or diminished during his or her term of office, except that when there are members elected or appointed to the Legislature or the judiciary, or officers elected or appointed to a board or commission having more than one member, and the terms of such members commence and end at different times, the compensation of all members of the Legislature, of the judiciary, or of such board or commission may be increased or diminished at the beginning of the full term of any member thereof.

Nothing in this section shall prevent local governing bodies from reviewing and adjusting vested pension benefits periodically as prescribed by ordinance.

The surviving spouse of any retired public officer, agent, or servant, who has retired under a pension plan or system, shall be considered as having pensionable status and shall be entitled to the same benefits which may, at any time, be provided for or available to spouses of other public officers, agents, or servants who have retired under such pension plan or system at a later date, and such benefits shall not be prohibited by the restrictions of this section or of Article XIII, section 3 of the Constitution of Nebraska.