On a Tuesday morning in a California federal courtroom, the most consequential legal challenge in Meta's history is set to begin. Thirty US states, led by California and New York, are placing before Judge Yvonne Gonzalez Rogers a single, damaging argument: that Instagram and Facebook were deliberately engineered to hook children, and that Meta profited from doing so. The damages being sought — upwards of $1 trillion — are almost as striking as the structural changes the states are demanding of a company currently valued at roughly $1.5 trillion on global stock markets.

The list of features the states want removed or restricted reads like a tour of everything that makes modern social media addictive. Infinite scroll, autoplay video, dopamine-driven recommendation algorithms, disappearing posts, appearance-altering filters and like counts — all of them, the plaintiffs argue, were consciously designed to maximise time on platform, including among teenagers and children. Frequent notifications, they add, make it genuinely difficult for young users to disengage. Meta has denied each of these claims forcefully.

"We strongly disagree with these allegations and are confident the evidence will show our longstanding commitment to supporting young people," a company spokeswoman said in a statement. The judge overseeing the case is no stranger to high-profile Silicon Valley disputes. Gonzalez Rogers presided over the Elon Musk v Sam Altman trial and has spent nearly two decades building a reputation for incisive, direct questioning from the bench. What makes this trial different from the string of earlier losses Meta has absorbed in court is its scale: a jury verdict against the company could mandate fundamental redesigns to platforms used by hundreds of millions of people across North America, Europe, and beyond.