Debra Messing arrives at the 75th annual Golden Globe Awards. (Jordan Strauss/Invision/AP)

The Golden Globes were infused with talk of gender inequality. Along with wearing black to show solidarity with the #MeToo movement, a number of celebrities made it a point to side with former “E! News” anchor Catt Sadler, who abruptly quit in December after she found out that she was paid half the amount her male co-anchor makes.

“I was so shocked to hear that E! doesn't believe in paying their female co-hosts the same as their male co-hosts,” Debra Messing said in a red carpet interview with the network.

E! says the pay disparity was related to workload rather than gender. But Sadler's story — and high-profile celebrities calling attention to it — underscores that pay discrimination exists in a legal gray area, about which Congress hasn't done much in more than 50 years.

That's a problem, say advocates of wage equality, because the phenomenon exists within the same power structure that perpetuates the sexual harassment of women in the workplace.

“Perceiving women as less valuable in the workplace and as a commodity that you can do what you like with — the power dynamics between sexual harassment and equal pay are very similar,” said Andrea Johnson, a state policy expert with the National Women's Law Center.

With pay equality apparently getting folded into the conversation on sexual harassment, here's a rundown of where equal-pay laws stand and where they might be going in the Trump era:

Where the law stands: The 1963 Equal Pay Act made it illegal for employers to pay a woman less than a man if they do similar work. But there's evidence that is still happening.

Women make on average 80 cents for every dollar a man makes, says Vicki Shabo, a vice president at the advocacy group National Partnership for Women and Families. Some of that is due to women gravitating toward lower-paying careers or bouncing in and out of the workforce as they balance being caretakers. But statistical analysis says that 38 percent of those 80 cents is unaccounted for, Shabo said.

It is easy enough for employers to offer reasons other than gender for paying a woman less, and the burden of proof is on the employee to prove otherwise.

Making things more difficult for women who think they are discriminated against is that an employer is legally allowed to retaliate if you make a big stink about what you perceive to be wage inequality. In some cases, employers sign confidentiality agreements preventing employees from even talking about how much they make.

“You can talk about it with your other colleagues and try to band together to address it,” Shabo said, “but there's a lot of gray around this.”

Recent changes to equal-pay laws: President Barack Obama bookended his tenure with two minor changes on pay equality. One of the first bills he signed into law was the Lilly Ledbetter Fair Pay Act, which removes the statute of limitations for women seeking to file a pay-discrimination claim.

In 2014, President Barack Obama signed executive actions aimed at closing a gender-based pay gap, as Lilly Ledbetter, the plaintiff in a pay-discrimination case, watched at left. (Susan Walsh/AP)

He lobbied for, and ultimately failed, to get Congress to pass more equal-pay legislation. So in his last years in office, Obama tried to take action himself. He signed an executive order requiring federal contractors to share how much they pay their employees and then expanded that to the private sector, authorizing a federal agency to collect pay data from large, private-sector companies.

Democrats have tried to push Obama's efforts, mainly in the form of the Paycheck Fairness Act, which has been introduced in Congress for two decades. It would require employers to give a concrete reason for why they pay someone less than someone else for the same job. It would allow people to sue for damages and make it more difficult for employers to retaliate against employees who talk about pay data.

It passed the House of Representatives twice in the early Obama years and came within two votes of passing the Senate in 2010. But a Senate Democratic aide said the bill became toxic for Republicans to support after Obama made equal pay a campaign issue in 2012.

Republican alternatives haven't moved forward either, says Kelly Dittmar, an expert of women in politics at Rutgers University.

Where pay-gap legislation could go in the Trump era: Probably nowhere. Republicans control Congress, and they've argued that more regulations on companies to bridge the pay gap would open them up to frivolous lawsuits.

One of President Trump's first actions was to end the Obama-era requirement that private companies share their employment data with the government.

But if we look outside Washington, states are moving in the opposite direction. In recent years, states such as California, New York and Massachusetts have strengthened their equal-pay laws by making it illegal for employers to rely on salary history when setting pay or by prohibiting employers from retaliating when their employees talk about wages.

It's not just progressive states that are moving toward equal-pay laws. Only two states (Alabama and Mississippi) have no equal-pay laws on the books, and Johnson said Mississippi is going to try to enact its first equal-pay law this year. Oklahoma also recently got very close to adopting such a law.

Talking about equal pay on the red carpet and actually getting federal equal-pay laws enacted are two very different things, but advocates say the headlines from the Golden Globes were a start.