When does a judge become a judge?

The answer to that question is at the heart of a lawsuit filed by six elected Superior Court judges who say they’ve been stiffed on their pensions.

Their complaint, filed in San Francisco Superior Court late last month, says that CalPERS and the state Judicial Council illegally shoved the six judges into a downgraded retirement plan. The less-lucrative program is part of a law Gov. Jerry Brown signed more than two years ago that, among other things, requires employees who join a pension fund on or after Jan. 1, 2013, to pay more for their benefits.

Superior Court Judges Louie Brooks Anderholt (Imperial County), Tara Flanagan (Alameda), Jennifer Giuliani (Kings), Gary Kreep (San Diego), Matthew McGlynn (Tehema) and Benjamin Wirtschafter (Yuba) were all elected in 2012.

The complaint filed by attorney Teague Paterson contends the judges became CalPERS members “upon their election to judicial office.” Some took their oath in late 2012, the lawsuit states. All started their new jobs on Jan. 7, 2013.

(State lawmakers and constitutional officers elected for the first time after 1990 don’t get a pension. Judges, who can be gubernatorially appointed or elected, still get a CalPERS retirement.)

At first, the six judges were enrolled in the better pension plan and paid the lower contribution rate, the lawsuit states.

Then a few months later, CalPERS informed the elected judges they actually were in the new pension plan and required them to contribute 6.25 percent more of their salary. They also had to pay the difference retroactively to January. Another 1 percent hike kicked in last year.

Meanwhile, Brown appointed approximately 30 judges at various times in 2012, according to the lawsuit, and the new pension formula hasn’t been applied to the appointees.

Paterson said the higher contributions put on his clients violate a constitutional provision that says salaries of elected state officers may not be reduced during their term of office.

“The law is clear,” Paterson said.

Prodded by the California Judges Association, the Legislature last year passed a bill that would have excluded the six judges from the higher payments. Brown vetoed it, saying he was “unwilling to begin chipping away” at the law.

CalPERS spokeswoman Rosanna Westmoreland said, “We agree with Governor Brown that the pension reform statute applies different requirements to judges who took office after the statute’s effective date than those who took office before its effective date.”

She wouldn’t comment directly about the active litigation. Neither would Cathal Conneely, spokesman for the Judicial Council.

So when is a judge a judge for pension purposes? Election? Appointment? Swearing in? First day on the job?

It looks like the courts will decide.