Gov. Gavin Newsom has signed a bill that will allow college athletes to use their name, image and likeness to endorse products. That runs directly opposite long-standing rules from the National Collegiate Athletic Association (NCAA) and could lead to a defining court battle.

The bill, which passed the California legislature unanimously, would go into effect in 2023. It stops the NCAA from barring a university from competition if athletes receive endorsements, ranging from major companies to paid youth coaching positions. Student athletes would also be allowed to hire agents.

The NCAA, in letters sent to the bill’s sponsor earlier this month, called it “unconstitutional” and a “scheme”. It also said it feared the bill would give California universities an unfair recruiting advantage, which could lead to them being barred from NCAA-sanctioned games.

The NCAA, which made over $1 billion in revenue in 2017, has long been criticized for not letting well-known college athletes cash in on their name, as pros can. California is the first state to sign such a bill into law, but others (including New York) are debating similar actions.

The bill had received the support of several pro athletes, including LeBron James, who celebrated Newsom’s signing on Instagram.

“To every one of you who have been in this fight (and there are a lot of you)- take a bow and be proud!!!!,” he wrote. “NCAA, you got the next move. We can solve this for everyone!”

More must-read stories from Fortune:

—The 25 most powerful women in politics
—Sanders vs. Warren: How their wealth tax plans differ
—Oprah has advice for the 2020 presidential candidates
—Higher U.S.-international postal rates loom before Christmas
—Can Andrew Yang win in 2020? Inside his unorthodox campaign

Get up to speed on your morning commute with Fortune’s CEO Daily newsletter.