At some point between 2019 and 2021, Arturo Béjar — a safety engineer at Meta — sent Mark Zuckerberg an email. It warned that Facebook and Instagram were generating a constant stream of harmful content for teenage users: recommendations surfacing material from sexual predators, violent imagery, and posts documented to damage adolescent wellbeing. Zuckerberg never wrote back. That silence sat at the centre of a federal courtroom in Oakland, California, this week, as Béjar became the first witness in what may prove to be the most consequential legal challenge the company has ever faced.

The trial was brought by attorneys general from 29 US states, who allege that Meta deliberately engineered addictive products that drew in young users and exposed them to measurable harm. Regulators also contend that the trillion-dollar company routinely collected personal data on children under the age of 13 without obtaining parental consent, in violation of both federal and state law. Béjar, who estimates he briefed Zuckerberg on product matters at least 100 times during his tenure, testified that he escalated child-safety concerns repeatedly to senior executives — and was consistently met with inaction. He characterised Meta's internal posture as a "don't ask, don't tell" strategy.

The trigger for his 2021 email to the CEO was a public statement in which Zuckerberg claimed the company did not place profit above safety. "I felt that he created a false and misleading impression of Facebook's commitment to young people," Béjar told the jury. The trial, which is expected to run for at least six weeks, will also hear testimony from Zuckerberg himself and from Instagram's CEO, Adam Mosseri, alongside expert witnesses on addiction and children's mental health.