In this June 23, 2014 photo, recruiter Christina O, with New Western Acquisitions, left, take Raheem Shaw's resumé during a job fair. (AP Photo/Matt Rourke)

If it remains true that California is the nation's test kitchen for new policy ideas, then employers around the country should look out.

Gov. Jerry Brown (D) plans to soon sign into law a new measure that would force employers facing gender wage discrimination claims to provide clear proof that men and women doing "substantially similar" work are paid differently for legitimate reasons, such as seniority or merit. That's a lot broader than California's existing law, which requires equal pay for those doing the exact same job.

And, there is something else: The new law extends actual protections to workers in the event that their employer should try to stop them or retaliate against them for doing something pretty essential in the fight against gender pay discrimination: asking a co-worker what they earn.

Basically, workers with similar responsibilities and work performance are supposed to be paid the same way. And women who suspect they are being underpaid won't have to rely on those rare but fortuitous occasions where they happen upon a colleagues' pay stub left behind in an old desk drawer or overhear a stray conversation in the break room.

Once the bill becomes law, it is poised to rank among the toughest in the nation, according to the Los Angeles Times.

The California bill, which will inevitably strike some Americans as excessive and unnecessary, aims to close one of the major gaps in existing anti-discrimination law. Women can and do bring gender-based wage suits, but these cases are notoriously difficult to prove in part because few private-sector employees have -- before lodging an internal or external complain, much less a lawsuit -- clear and irrefutable evidence of their co-workers' pay. Even fewer have access to multiple co-workers' pay information to spot and prove persistent patterns.

Employers across the country have instituted rules or at least made firm suggestions that employees avoid sharing the details of their compensation with co-workers. Technically both are illegal, but the practices remain widespread and have, at this point, joined the list of things that shrewd employees should, allegedly, never do. The culture of secrecy around pay remains so pervasive that last year President Obama signed a pair of executive orders aimed at drawing attention to the freedom of employees to discuss their wages and requiring federal contractors to supply the U.S. Labor Department with more information about the wages they pay.

Add to that the excess media attention given to the few areas in New York and other major metros where women now make more than men, pundits who argue that the gender wage gap is really a matter of women opting to limit work hours, and the negligible share of people who will admit to contributing the gender wage gap, and it can get hard to understand why so many women still earn far less than men.

But the data is clear. Just take a look at the most recent figures from the Labor Department's Bureau of Labor Statistics:

In fact, gender and racial pay gaps tend to compound one another, as white women often earn more than non-white men. Some of this, is, of course, a reflection of educational attainment and time in the workforce. Non-white workers are, on average, less-educated and younger than white workers. But the emphasis here really has to be placed on the word "some."

Some of the data above is also a reflection of ongoing racial and gender discrimination -- social forces that compound one another -- in the workforce. Together they help to sustain long-term patterns of racial, ethnic and gender clustering in certain industries and on the low rungs of the nation's pay ladder. And, this isn't just a function of which adults are responsible or generational belief in gender stereotypes or expectations. Gender and racial/ethnic wage gaps show up when you look at weekly earnings for teenagers, too. And, they remain when you compare different groups of workers with the same amount of education.

Those patterns matter not just for individual women and their egos. Beginning in 2013, in fact, women were the primary or sole breadwinner in 40 percent of American households.

Now, before you begin contemplating an immediate move to California, consider this: In the very legislative bodies that voted in favor of the bill and sent it to the governor's desk, there's a gender pay gap, too. In California's Democratic-controlled House, female staffers earn, on average, 92 cents for every dollar their male counterparts are paid, according to the Sacramento Bee. And in the Democratic-dominated state Senate, women fair just slightly better, bringing in 94 cents for every dollar earned by their male colleagues.

It appears there's work to do in the test kitchen, too.