A San Francisco judge has sided with a state employee union in a lawsuit against Gov. Arnold Schwarzenegger over the legality of worker furloughs.

The ruling found the governor overstepped his authority when he ordered 7.400 workers for the State Compensation Insurance Fund to take three furlough days per month.

It was not immediately clear what implications, if any, the ruling from Superior Court Judge Charlotte Woolard would have on the more than 200,000 workers who are currently subject to three forced furlough days per month.  

Schwarzenegger administration officials have said they will appeal the ruling.

The decision is in response to a suit brought by the Service Employees International Union Local 1000, which represents more than 6,000 SCIF workers. The union has four other lawsuits pending challenging the legality of the forced furloughs.

But it was unclear what impact this week’s ruling would have on those other cases. There are specific previsions in the state insurance code that exempt state fund workers from “any hiring freeze and staff cutbacks otherwise required by law.”

“Insurance Code section 11873(c) exempts State Compensation Insurance Fund employees from the furlough,” Woolard ruled. “A ‘furlough’ reduces the availability of staff and constitutes a ‘staff cutback.’ The petition is granted and the writ shall issue.”

Still, union leaders hailed this week’s ruling as a major victory.

 “This is another crack in the governor’s illegal furlough scheme,” said Local 1000 President Yvonne Walker.  “We will continue our litigation in all possible venues.”

While waging a legal fight against the administration, Local 1000 has also begun a public relations push against Schwarzenegger’s furlough plan. Last month, the union launched statewide radio ads attacking the work stoppages.

The ads claim “Schwarzenegger broke his word…He’s refusing to support the agreement he negotiated. Governor, keep your word.  That’s what real leaders do.  Support the contract you negotiated.”

But the furlough fight is far from over.

Other judges have upheld Schwarzenegger’s general furlough authority. In March, a Sacramento judge ruled he had the authority to furlough about 15,000 state workers employed by California’s constitutional officers and the Board of Equalzation.

Many of the state’s Democratic constitutional officers -- including Controller John Chiang, Treasurer Bill Lockyer, Attorney General Jerry Brown, Lieutenant Gov. John Garamendi and Secretary of State Debra Bowen -- had refused to abide by Schwarzenegger’s initial furlough order. But Judge Patrick Marlette sided with the governor in that case.

The state’s lone Republican constitutional officer, Insurance Commissioner Steve Poizner, also challenged the governor’s furlough authority.

Schwarzenegger has ordered three furlough days per month for most state workers in an effort to close the state’s budget gap. The furloughs amount to a 14 percent pay cut for the workers affected. The state has scored about $1.4 billion in savings from the furlough program.