The bill defines “addiction” as kids under 18 who are both harmed — either physically, mentally, emotionally, developmentally or materially — and who want to stop or reduce how much time they spend on social media but they can’t because they are preoccupied or obsessed with it.

Business groups have warned that if the bill passes, social media companies would most likely cease operations for children in California rather than face the legal risk.

The proposal would only apply to social media companies that had at least $100 million in gross revenue in the past year, appearing to take aim at social media giants like Facebook and others that dominate the marketplace.

It would not apply to streaming services like Netflix and Hulu or to companies that only offer email and text messaging services.

“The era of unfettered social experimentation on children is over and we will protect kids,” said Assemblymember Jordan Cunningham, a Republican from San Luis Obispo County and author of the bill.

Monday’s vote is a key - but not final — step for the legislation. The bill now heads to the state Senate, where it will undergo weeks of hearings and negotiations among lawmakers and advocates. But Monday’s vote keeps the bill alive this year.

The bill gives social media companies two paths to escape liability in the courts. If the bill becomes law, it would take effect on Jan. 1. Companies that remove features deemed addictive to children by April 1 would not be responsible for damages.

Also, companies that conduct regular audits of their practices to identify and remove features that could be addictive to children would be immune from lawsuits.

Despite those provisions, business groups have opposed the bill. TechNet, a bipartisan network of technology CEOs and senior executives, wrote in a letter to lawmakers that if the bill becomes law “social media companies and online web services would have no choice but to cease operations for kids under 18 and would implement stringent age-verification in order to ensure that adolescents did not use their sites.”

“There is no social media company let alone any business that could tolerate that legal risk,” the group wrote.

Lawmakers appeared willing to change the part of the bill that allows parents to sue social media companies, but none offered a detailed alternative. Instead, supporters urged their colleagues to pass the bill on Monday to continue the conversation about the issue in the state Capitol.

Assemblymember Ken Cooley, a Democrat from Rancho Cordova, said as a lawyer he normally opposes bills that create more opportunities for lawsuits. But he said lawmakers must “change the dynamics of what is surrounding us, surrounding our kids.”

“We have to do something,” he said. “If it doesn’t turn out right we can modify as we go along.”