What the law bans

Assembly Bill 1709 prohibits platforms from offering underage children what the law calls "psychologically exploitative features" that could lead to compulsive use. Governor Gavin Newsom signed it on 10 September, saying California "will not stand by while unregulated technology puts our children at risk". It takes effect on 1 January 2027 unless a judge voids it or puts it on hold.

The features in the law's sights include:

• •personal recommendations shown to children
• •videos delivered through autoplay
• •a requirement to delete children's accounts that carry those features

The companies' arguments

Google, Meta and TikTok each brought their own case on Wednesday. In their view, the measure forces them to follow how California prefers content presented to children, taking that decision out of parents' hands. They contend it violates the US constitution's First Amendment free speech protections as well as Section 230 of the federal Communications Decency Act.

Google spokesperson Jose Castaneda said on Thursday: "Parents are best positioned to make the right decisions for their families." He added that "Overly broad laws like this actually break the systems we've built to help kids find high-quality, age-appropriate videos."

TikTok's filing argued that protected speech "cannot be suppressed solely to protect the young from ideas or images that a legislative body thinks unsuitable". Meta's suit says California cannot override its editorial judgments about how to curate and display billions of posts while children can spend unlimited time on comparable platforms.

California's response and courtroom map

The only defendant named is California attorney general Rob Bonta. His office said on Thursday it was reviewing the lawsuits, adding: "Our office is committed to defending California's commonsense laws to protect kids online."

The three cases landed in three different courtrooms:

• •Google filed in federal court in San Jose, California
• •Meta sued in San Francisco
• •TikTok sued in Los Angeles

A wider legal landscape

The suits join a crowded field. Many US states regulate children's social media access, and countries worldwide have similar restrictions, including Australia's ban on social media for children under 16. Meta, for its part, reached settlements in August with nearly every US state over privacy and consumer protection allegations, committing to payments of up to $18bn and to curbing how teenagers use Facebook and Instagram.

Together with Snap, the companies also remain defendants in thousands of suits brought by individuals, school districts, municipalities and other government entities alleging they worked to addict children, causing anxiety, depression and suicide.

Unless a judge strikes the law down or pauses it, it comes into force on 1 January 2027; the attorney general's office is weighing the challenges.