Google, Meta and TikTok have sued California to block enforcement of ⁠a new state law intended ⁠to limit the risk ​of addicting children under 16 to social media platforms.

The law, known as Assembly Bill 1709, prohibits such platforms from offering underage children “psychologically exploitative features” that could lead to compulsive use, such as providing ⁠personal recommendations and sending videos through autoplay features. It also requires the deletion of children’s accounts with those features.

In separate lawsuits on Wednesday, Google, Meta and TikTok said the law wrongly compels them to honor California’s preferred means of ⁠presenting content to children and substitutes the state’s judgment for that of parents.

They said the law violates the US constitution’s first amendment free speech ​protections, as well as Section 230 of the federal Communications Decency ‌Act, which broadly shields online platforms from ‌liability over user content.

The office of Rob Bonta, the California attorney general, who enforces the state’s laws and is the only defendant, said ‌on Thursday it was reviewing the lawsuits. “Our office is committed to defending California’s commonsense laws to protect kids online,” it added.

Google owns YouTube and is a unit of Alphabet, while Meta owns Facebook and Instagram. TikTok is a unit of China’s ByteDance.

Governor Gavin Newsom signed the law on 10 September, saying children’s safety should be central to any discussion about technology, and California “will not stand by while unregulated technology puts our children at risk”.

The law takes effect on 1 January 2027, unless a judge voids it or puts ‌it on hold.

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

In its ​lawsuit, Meta said California cannot override its editorial judgments about how to curate and display billions of posts, while leaving children free to spend unlimited time on other online platforms that offer similar services.

TikTok, meanwhile, said protected speech “cannot be suppressed solely to protect the young from ideas or images that a legislative body thinks unsuitable”.

Other critics also accused California of overreaching. The Electronic Frontier Foundation, a non-profit digital rights advocacy group, called the law “a massive ⁠privacy and free speech nightmare”.

Many US states regulate children’s access to social media. Countries ​around the world have similar restrictions, including a ​ban in Australia on social media for children ​under 16.

In August, Meta agreed to pay up to $18bn and limit teenagers’ use of Facebook and Instagram ​under agreements with nearly all US ‌states, which accused it ​of violating privacy and consumer protection ​laws.

In the aftermath of whistleblower revelations that showed Meta was aware of the way its platforms harmed teens, Meta launched a suite of teen safety tools aimed at giving parents more oversight. The company has previously tapped influencers to promote these features around the world as an alternative to social media bans or limitations similar to Australia’s.

Google has come under fire more recently over the use of its AI tools on school devices. On Thursday, parents in California filed a lawsuit against the company alleging their teen daughter made plans to end her life after multiple interactions with AI mode on Google Search. She had access to the AI mode through her school-issued Google Chromebook. The company was also recently forced to backtrack on its decision to cut off a school or classroom’s access to Google Search if teachers or administrators decided not to enable Google’s other AI features for schools.

Google filed its lawsuit in federal court in San Jose, California. Meta sued in San Francisco, and TikTok sued in Los Angeles.

The companies and Snapchat parent Snap still face thousands of lawsuits by individuals, school districts, municipalities and other government entities claiming they sought to addict children and caused a mental health crisis that resulted in such harms as anxiety, depression and suicide.