MARTINEZ -- The state Attorney General's Office seeks to consolidate into Contra Costa four county public employee union lawsuits that challenge 2012 pension anti-spiking legislation.

Contra Costa was the first case filed, involves the largest number of employees, and the county is the most centrally located, deputy attorney general Anthony O'Brien told Superior Court Judge David Flinn this week.

"We want to move as quickly as possible and get to the hearing on the merits of the case," O'Brien said.

The other lawsuits were filed in Alameda, Marin and Merced counties.

At issue is the inclusion of unused vacation, sick or other types of "terminal leave" to increase or "spike" an employee's retirement income.

Contra Costa public employee unions say they will oppose the merger when the judge hears arguments in May.

Pension rules vary between counties and merging the cases could dilute key facts in the Contra Costa case, said attorney Rocky Lucia, who represents the Contra Costa Deputy Sheriffs Association and the United Professional Fire Fighters Local 1230.

"I am concerned our case will get caught up in the vortex," Lucia said.

The high-stakes legal showdown centers around Assembly Bill 197, an anti-spiking pension measure authored by Assemblywoman Joan Buchanan, D-Alamo. It came on the heels of AB340, which contained the bulk of the pension reforms sought by Gov. Jerry Brown.

AB197 bars the inclusion of unused vacation, sick and other types of "terminal leave" in an employee's retirement calculation formula beyond what he or she would earn in a year.

The Contra Costa County Employees Retirement Association board had already prohibited the use of terminal pay for all employees hired starting Jan. 1, 2013.

But after AB197 passed, the pension board reluctantly stripped the perk away from existing employees, based on advice from retirement association attorney Harvey Leiderman.

Marin, Alameda and Merced pension boards did the same.

The unions sued and judges stayed implementation of the new law until the litigation is resolved.

In Contra Costa, losing terminal pay would shave 10 percent to 16 percent off future monthly retirement checks for firefighters in the Contra Costa, San Ramon Valley, Moraga-Orinda, Rodeo-Hercules and East Contra Costa fire districts, according to the association.

Sheriffs deputies would lose an average 11 percent. Central Contra Costa Sanitary District workers would see the biggest average drop -- 24 percent.

The exact amount will depend on a worker's age, years of service and pay rate. No current retiree's benefit is affected by the new rules.

Lucia argues the Contra Costa County Employees Retirement Association board improperly applied the terminal pay ban retroactively.

Courts have consistently upheld promised or vested pension benefits as a contractual obligation, he said.

Terminal pay as a component of the retirement formula had been promoted in the association's handbook for many years, and employers and employees have paid for the benefit in their contribution rates, Lucia said.

While the four county retirement associations had adopted rules consistent with AB197, they have refused to defend it in court. It is up to the state to make its case, the pension boards said.

Gov. Brown directed the Attorney General's Office in early February to defend the legislation.

State attorneys haven't yet divulged their legal arguments on whether legislation violates vested rights.

Instead, the state is focused on securing legal standing to defend the legislation, even though California wasn't named in the lawsuits.

The state did argue in court documents, however, that AB197 was written to ensure financial solvency in the handful of retirement systems statewide where employees could parlay unused leave into higher lifetime monthly payments.

Contact Lisa Vorderbrueggen at 925-945-4773, lvorderbrueggen@bayareanewsgroup.com, politicswithlisav.blogspot.com or Twitter.com/lvorderbrueggen.