Mark Zuckerberg to testify in landmark social media addiction trial

Meta CEO Mark Zuckerberg is set to testify Wednesday at a groundbreaking social media addiction trial, summoned by lawyers representing a plaintiff who alleges 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 in a series of cases that could set legal precedent for thousands of lawsuits filed by American families against major social media platforms.

The trial will mark the first time the multibillionaire will address the safety of his world-dominating platforms directly before a jury.

Zuckerberg's controversial reputation has loomed over the proceedings since jury selection, when Meta's lawyers worked to exclude California residents deemed too 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 problems suffered by Kaley G.M., a 20-year-old California resident who has been a heavy social media user since childhood.

Kaley G.M. started using YouTube at age 6, Instagram at 11, then TikTok and Snapchat.

The trial will determine whether Google and Meta deliberately designed their platforms to encourage compulsive use among young people, damaging their mental health in the process.

The case, along with two similar trials scheduled in Los Angeles this summer, aims to establish a standard for resolving thousands of lawsuits that blame social media for fueling an epidemic of depression, anxiety, eating disorders and suicide among young people.

The proceedings focus solely on app design, algorithms and personalization features, since US law grants platforms nearly complete immunity from liability over 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 February 11, in which he told jurors he rejected the concept of social media addiction in favor of "problematic use" -- Meta's preferred terminology.

"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 visibly struggled to contain their anger. They 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 behaviors.

When confronted with internal email exchanges, Mosseri defended Zuckerberg's 2020 decision to allow cosmetic surgery filters on Instagram, despite strong 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 look -- to avoid losing market share amid growing competition from TikTok.

YouTube CEO Neal Mohan was also scheduled to testify, but lawyers for the plaintiff on Tuesday said they would call another YouTube executive instead.

The Los Angeles proceedings are running parallel to a similar nationwide case before a federal judge in Oakland, California, which could result in another trial in 2026.

Meta is also facing trial this month in New Mexico, where prosecutors accuse the company of prioritizing profits over protecting minors from sexual predators.