Meta trial that could reshape social media starts in US

A coalition of US states suing Meta Platforms over claims Facebook and Instagram were designed in ways that harmed young users' mental health has begun making its case in California federal court, in a trial that could reshape some of the most popular apps on the planet.

Megan O'Neill, a deputy California attorney general, told the eight-person jury in Oakland, California, that Meta's business model was to "hook the users, hold them for as long as they can, harvest their data, and then hide the truth from the public".

O'Neill told the jury the case was not about taking away Instagram or social media.

"This case is not about whether social media has some benefits for some people. It does," she said.

California, Colorado, Kentucky and New Jersey are leading a bipartisan group of 29 states suing Meta.

Jurors are expected to issue an advisory verdict but US District Judge Yvonne Gonzalez Rogers will determine Meta's liability.

If she finds Meta liable, Rogers could impose civil penalties and order changes to Facebook and Instagram.

The trial will address claims by the four lead states that Meta designed Facebook and Instagram to addict young children and teenagers, resulting in such harms as anxiety, depression and even self-harm, and misled consumers about the platforms' safety.

"Meta needed kids, and it needed to reassure the people who cared about those kids that the kids are safe," O'Neill said.

Jurors will also hear claims by all 29 states that Meta violated federal law by improperly collecting and using personal data of children while they used its platforms.

Lawyers for Meta are expected to tell the jury that the company has made a huge effort to keep kids safe online.

Meta has said it did not make misleading statements about safety, and the states failed to show their residents were harmed.

Meta co-founder and CEO Mark Zuckerberg and Instagram chief Adam Mosseri are expected to testify.

Experts have said the trial is the biggest legal test yet of social media's effects on young users, and comes amid a broader reckoning across the globe over those effects.