Female workers in California are getting new tools to challenge gender-based wage gaps under legislation that supporters say offers the strongest equal-pay protection in the nation.

Democratic Gov. Jerry Brown signed the measure Tuesday while surrounded by women and girls at an event at Rosie the Riveter National Historical Park in Richmond, northeast of San Francisco.

The bill by Sen. Hannah-Beth Jackson, a Santa Barbara Democrat, expands California's existing equal pay law and goes further than federal law by placing the burden on the employer to prove a man's higher pay is based on factors other than gender.

It also protects workers from discrimination and retaliation if they ask questions about how much other people earn, though it doesn't require that employers provide that information. Workers also will gain the right to sue if they are paid less than someone with a different job title who does "substantially similar'' work.

The Fair Pay Act stipulates employers can justify higher wages for men only if the pay is based on seniority, a merit system, quantity or quality of production or any other "bona fide factor other than sex.'' It cleared the Legislature with bipartisan support and backing from the state Chamber of Commerce.

The new law takes effect Jan. 1.

Brown also is considering a bill that aims to end the cycle of women's wages lagging behind men's pay by barring employers from using previous salary information as justification for paying women less than their male co-workers.

Some lawmakers balked at approving the measure, by Assemblywoman Nora Campos, D-San Jose, noting the California State Legislature itself uses previous salary information to set employees' wages.

Some state lawmakers say they were motivated to pursue equal pay legislation by heartfelt pleas from high-profile Hollywood actresses at this year's Academy Awards. Lawyer Ellen Pao also made national waves when she filed a gender discrimination lawsuit against a prestigious venture capital firm in Silicon Valley.

While she lost, the publicity prompted embarrassed soul-searching in an industry dominated by male managers.