Meta CEO Mark Zuckerberg is set to testify on Wednesday in a landmark social media addiction trial, summoned by lawyers representing a plaintiff who alleges that Instagram and other platforms were deliberately designed to make young users addicted.
The 41-year-old head of Meta—which owns Facebook, Instagram, and WhatsApp—is the most anticipated witness in the California trial, the first of several cases that could establish legal precedent for thousands of lawsuits filed by American families against major social media platforms.
The trial marks the first time the multibillionaire will directly address the safety of his globally dominant platforms before a jury.
Zuckerberg’s controversial reputation has hung over the proceedings since jury selection, when Meta’s lawyers sought to exclude California residents considered hostile toward the Facebook founder.
The 12 jurors in Los Angeles will hear testimony until late March to decide whether Google-owned YouTube and Meta’s Instagram bear any responsibility for the mental health issues experienced by Kaley G.M., a 20-year-old Californian who has been a heavy social media user since childhood.
Kaley G.M. began using YouTube at age six, Instagram at 11, and later TikTok and Snapchat.
The trial will determine whether Google and Meta deliberately engineered their platforms to encourage compulsive use among young people, harming their mental health in the process.
Along with two similar trials scheduled in Los Angeles this summer, the case aims to set a standard for resolving thousands of lawsuits alleging that social media fuels an epidemic of depression, anxiety, eating disorders, and suicide among young people.
The proceedings focus solely on app design, algorithms, and personalisation features, as US law grants platforms almost complete immunity from liability for user-generated content.
TikTok and Snapchat, also named in the complaint, reached confidential settlements with the plaintiff before the trial began.
Problematic use
Instagram chief Adam Mosseri was the first Silicon Valley executive to testify on 11 February, telling jurors he prefers the term “problematic use” over “addiction”.
“I’m sure I’ve said that I was addicted to a Netflix show when I binged it really late one night, but I don’t think that’s the same thing as clinical addiction,” Mosseri said.
In the courtroom gallery, mothers whose teenage children had died by suicide struggled to contain their anger; many had camped overnight in the rain outside the courthouse to secure seats.
The day before, the plaintiff’s lawyers called psychiatrist Anna Lembke to explain how social media can act as a “gateway drug” for young people, rewiring their still-developing brains toward addictive behaviours.
When confronted with internal email exchanges, Mosseri defended Zuckerberg’s 2020 decision to allow cosmetic surgery filters on Instagram, despite objections from other executives who warned of their harmful effects on young girls.
Some executives had pushed to reinstate the filters—which show users how cosmetic procedures would appear—to avoid losing market share amid growing competition from TikTok.
Neal Mohan was also scheduled to testify, but the plaintiff’s lawyers said on Tuesday they would call another YouTube executive instead.
The Los Angeles proceedings run parallel to a similar nationwide case before a federal judge in Oakland, California, which could lead to another trial in 2026.
Meta is also facing trial this month in New Mexico, where prosecutors accuse the company of prioritising profits over protecting minors from sexual predators.
