"Furlough Fridays" came under legal attack again Wednesday, this time from CalPERS.

The $190 billion pension fund sued Gov. Arnold Schwarzenegger and other state officials, saying the unpaid three-days-a-month furloughs of its employees are jeopardizing CalPERS' ability to serve California's retirees at a time of nonstop turmoil in the financial markets. It also said CalPERS furloughs generate no savings to the state's budget because its 2,000 employees are paid out of the pension fund's internal sources.

Schwarzenegger imposed two unpaid furlough days a month on most state workers in February and added a third furlough day in July. The California Public Employees' Retirement System was trying to cope with the furloughs but "the third day exacerbated the harm," said CalPERS spokeswoman Pat Macht.

The suit, filed in San Francisco Superior Court, argues that furloughing CalPERS employees could actually backfire on the state: If the furloughs hinder CalPERS' ability to rebound from huge investment losses, they will increase the funding burden on the state budget.

CalPERS has already warned that taxpayer contributions to the fund will go up starting next summer to compensate for a record $56 billion investment loss.

The furloughs "deprive CalPERS of full staffing exactly at the time when it must be at full capacity," the suit said.

The furloughs, in cutting employees' wages by nearly 15 percent, have become a huge economic issue. In Sacramento, where nearly one in 10 employees works for the state, the furloughs will take roughly $500 million out of the economy by the time the program ends next June, according to a Bee analysis.

Schwarzenegger spokesman Aaron McLear said it makes no difference that CalPERS employees aren't paid out of the general fund. Furloughs help the state's cash flow "regardless of where the employees are paid from," he said.

"Just like the rest of state government, they need to figure out how to operate more efficiently," he added.

CalPERS officials have hinted for weeks that they were studying the legality of the furloughs.

The state's other big pension fund, the California State Teachers' Retirement System, Wednesday formally asked State Controller John Chiang for relief from the furloughs.

"It's too early to say if we'll be involved in a lawsuit. We certainly share the common objective with our sister pension fund," said CalSTRS spokeswoman Vonnie Madigan.

Like CalPERS, the teachers pension fund does not receive money from the state general fund. "Our members pay out of their paychecks for our services," Madigan said. "It's really affected our ability to serve folks, and they don't understand why."

Madigan said the furloughs have also prompted some of the fund's most veteran employees to consider retiring rather than take the financial hit.

The CalPERS lawsuit joins a host of others that have argued Schwarzenegger overstepped his legal authority by imposing the furloughs.

So far Schwarzenegger has beaten back almost every challenge, fending off suits filed by the giant Service Employees International Union Local 1000 and several other unions. He also successfully sued the state's constitutional officers, such as Lt. Gov. John Garamendi, for refusing to furlough their 15,000 workers.

Only one group, representing 500 legal professionals, has prevailed against Schwarzenegger.

All of the cases are on appeal.

Call The Bee's Dale Kasler, (916) 321-1066. Read his blog on the economy, Home Front, at www.sacbee.com/blogs.