Patricia Arquette, state lawmakers and activists predicted that California’s new equal pay law, which goes into effect on Friday, will have a significant impact on Hollywood and other industries.

Arquette, who championed the issue of equal pay for women across all workplaces during her Oscar speech after winning for “Boyhood” this year, said that when it comes to entertainment, “in general, [employers] are going to have to make a radical readjustment, and they know that, because they know for decades they have been paying unfairly.”

Arquette appeared at a press conference at the Amelia Earhart Library in North Hollywood on Wednesday along with California State Sen. Hannah-Beth Jackson, the author of the California Fair Pay Act, along with other lawmakers including State Senate Pro Tem Kevin de Leon.

The law, considered the toughest in the nation, maintains that employers cannot pay male and female employees differently for doing “substantially similar” work. The legislation was a revision of current law, on the books since the 1940s, that has been interpreted by courts to mean that equal play applied only to workers who hold exactly the same jobs.

The law does have a number of exceptions, allowing for pay disparity if earnings are measured by the “quantity and quality of production.” Another exception is if an employer has a “bona fide” reason other than gender for disparate pay, such as education, training or experience, and if the pay differential is out of “business necessity.”

Those could be used as justifications for say, paying a lead actor or lead actress on the same project differently. Arquette noted that there were reasons unique to entertainment that factor into the way that performers are paid.

“When you work in TV, you have something called a TVQ as an actress,” she said. “So that is kind of your rating, how many people recognize you on TV. There’s a value to that. There is a value to that you won an award. So obviously the industry will be trying to show different values and how things make sense.”

But she and Jackson said that employers now will have to give legitimate reasons for disparity in pay between genders.

“This is happening to women whether they make $10 million for a movie or whether they make $10 an hour,” Jackson said. “Women are not being paid for the fair value of their work, and that is the problem, and that is what needs to change. And because Hollywood has been taking the lead, and Patricia took the lead within the lead, we are hearing more about it. But this applies to all women.”

Arquette’s Oscar speech gave momentum to the legislation, Jackson said, and the entertainment industry has played a role in elevating the issue. She said that awareness of the new law will help shift the culture in the workplace, perhaps getting employers to shift their practices on their own without an employee having to resort to litigation. The law also includes a provision barring retaliation for discussing or inquiring about another employee’s pay.

The issue of pay inequality has gotten greater attention in Hollywood throughout 2015.

Arquette cited the Sony hack as letting “us know about this pay inequality, not just for actresses, but women working in editing, special effects, all the way down in every area.”

That included the revelation that Jennifer Lawrence was paid less than her male costars in “American Hustle.” Arquette said that what the industry is facing is a shift in mindset.

“Jennifer Lawrence pays someone to negotiate on her behalf. But guess what, she is paying the same person those guys are paying,” Arquette said. “And yet subconsciously, their agents think, ‘This is just the status quo, this is the way the business is.’ They have allowed that to happen. The people she has been paying, and every woman has been paying Hollywood, have been allowing them to be undervalued. Their managers, Their agents. The studio. Everybody has to make a shift and go ‘Wait a second, dude, we know you are paying him whatever.'”

De Leon said that although entertainment had different methodologies to determining pay, “there is no special exemption for the Hollywood community, or for that matter any other community. Pay is pay, and this issue applies across the board equally.”