MIAMI – With the state preparing for a legal challenge from the tech industry, Gov. Ron DeSantis on Monday signed a high-profile bill aimed at keeping children off social media platforms.

“You better believe, I am going to fight like hell to uphold this in court,” Attorney General Ashley Moody said during a bill-signing event in Jacksonville.

Lawmakers this month overwhelmingly passed the bill (HB 3), which House Speaker Paul Renner, R-Palm Coast, made a priority of the annual legislative session. The bill, in part, seeks to prevent children under age 16 from opening social media accounts on at least some platforms — though it would allow parents to give consent for 14- and 15-year-olds to have accounts. Children under 14 could not open accounts.

Renner and other key supporters argue that social media companies have created addictive platforms that harm children’s mental health and can lead to sexual predators communicating with minors. But critics, including tech-industry groups, argue the bill is unconstitutional and point to courts blocking similar legislation in other states.

The industry group NetChoice this month urged DeSantis to veto the measure, arguing it would violate First Amendment rights. Spokeswoman Krista Chavez said in an email Monday that the group does not publicly discuss legal strategy, but it quickly recirculated the veto request and earlier statements about the constitutionality of the bill.

“An unconstitutional law will protect exactly zero Floridians,” Carl Szabo, NetChoice’s vice president and general counsel,” said in a statement. “HB 3 is also bad policy because of the data collection on Floridians by online services it will in effect require. This will put their private data at risk of breach.”

Renner, however, said the bill focuses on addictive features of the platforms and not on social-media content — an approach that he said is designed to withstand a First Amendment challenge.

“You will not find a line in this bill that addresses good speech or bad speech because that would violate the First Amendment. We’ve not addressed that at all,” Renner, an attorney, said. “What we have addressed is the addictive features that are at the heart of why children stay on these platforms for hours and hours on end.”

The bill does not name social media platforms that would be affected. But it includes a definition of such platforms, with criteria related to such things as algorithms, “addictive features” and allowing users to view the content or activities of other users.

DeSantis, also an attorney, vetoed an earlier version of the bill (HB 1) after raising concerns about constitutional issues and infringement on parental rights. But he negotiated with Renner on the plan that was signed Monday.

A significant change was that the revised plan would allow 14- and 15-year-olds to open accounts with parental consent. The earlier version would have prevented 14- and 15-year-olds from creating accounts without a parental consent option.

In another change, the earlier version would have directed age-verification requirements for platforms. Those requirements would have affected adults creating accounts.

But the revamped plan does not include the requirements. As an alternative, supporters hope to ensure compliance by opening social-media platforms to lawsuits for violations of the age restrictions. That would include lawsuits filed by the attorney general and lawsuits filed on behalf of minors.

If the tech industry files a lawsuit, it would be the second major court fight against Florida social-media laws in recent years.

NetChoice and another industry group, the Computer & Communications Industry Association, challenged the constitutionality of a 2021 Florida law that placed restrictions on large social-media companies, such as preventing the platforms from banning political candidates from their sites and requiring companies to publish — and apply consistently — standards about issues such as banning users or blocking their content.

Federal courts have blocked much of that law on First Amendment grounds. Florida took the case to the U.S. Supreme Court, which heard arguments last month but has not issued a ruling.

During Monday’s bill-signing event, Renner said he expects NetChoice to file a lawsuit over the new law, which will not take effect until Jan. 1. But Renner expressed confidence that the state will win in court and cited dangers of social media to children.

“This is an issue where we can no longer stand on the sidelines because of what we know,” he said.

The bill also will require age verification to try to prevent minors under age 18 from having access to online pornographic sites, though that issue received relatively little attention during legislative debates.