Meta CEO Mark Zuckerberg is set to testify on Wednesday in a landmark trial in Los Angeles that targets alleged social media addiction.

Lawyers representing a plaintiff say Instagram and other platforms were deliberately designed to make young users addicted. Zuckerberg, 41, is described as the most anticipated witness in the California case, which is the first in a series of trials that could shape legal precedent for thousands of lawsuits filed by American families.

The trial is expected to be the first time Zuckerberg addresses the safety of Meta’s major platforms directly before a jury, the report says.

What the Jury Must Decide

A 12-person jury will hear testimony until late March. They will 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, according to the report.

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

The court will consider whether Google and Meta deliberately designed their platforms to encourage compulsive use among young people and whether that damaged mental health, the report says.

Focus on Design and Algorithms

The proceedings focus on app design, algorithms and personalisation features. The report notes this is because US law gives platforms near-total immunity from liability over user-generated content.

TikTok and Snapchat were also named in the complaint but reached confidential settlements with the plaintiff before the trial began, according to the report.

‘Problematic Use’ and Emotional Scenes in Court

Instagram chief Adam Mosseri testified on 11 February. He rejected the concept of social media addiction and said Meta prefers the term “problematic use”, the report says.

In the courtroom gallery, mothers whose teenage children died by suicide reportedly struggled to contain their anger after camping outside the courthouse overnight to secure seats.

Psychiatrist Anna Lembke testified that social media can act as a “gateway drug” for young people and can rewire developing brains towards addictive behaviours.

Zuckerberg’s testimony is expected to be a turning point in a case that could influence how thousands of similar lawsuits are handled.