Meta Chief Executive Officer Mark Zuckerberg is expected to testify on Wednesday in a closely watched social media addiction trial in California, marking the first time he will address a jury over the safety of the company’s platforms.
The case, being heard in Los Angeles, centres on allegations that Instagram and other platforms owned by Meta were deliberately designed to encourage compulsive use among young users, contributing to mental health harm.
Zuckerberg, 41, is considered the highest-profile witness in the trial, which is the first in a series of lawsuits filed by American families against major technology companies. The outcome could influence thousands of similar claims pending across the United States.
Jurors are examining whether Instagram and Google-owned YouTube bear responsibility for mental health issues suffered by a 20-year-old plaintiff, identified in court filings as Kaley G.M., who has used social media since early childhood. According to filings, she began using YouTube at age six and joined Instagram at 11, later expanding to TikTok and Snapchat.
The lawsuit alleges that platform features such as algorithms and personalised content were structured to maximise engagement in ways that encouraged excessive use among minors. TikTok and Snapchat, initially named in the complaint, reached confidential settlements with the plaintiff before trial.
The trial focuses on product design and platform mechanics rather than user-generated content, as federal law generally shields companies from liability over content posted by users.
Earlier this month, Instagram chief Adam Mosseri testified, disputing the characterisation of social media use as addiction and instead referring to it as “problematic use.” He told jurors that heavy engagement does not necessarily equate to clinical addiction.
The plaintiff’s legal team has also presented expert testimony, including from psychiatrist Anna Lembke, who argued that certain digital platforms can reinforce compulsive behaviours, particularly among young users.
The proceedings are expected to continue through late March. Two additional trials involving similar claims are scheduled in Los Angeles later this year.
Separately, Meta faces other legal challenges, including a nationwide case before a federal judge in Oakland, California, and a criminal case in New Mexico, where prosecutors allege the company failed to adequately protect minors online.
The outcome of the Los Angeles trial is widely viewed as a potential benchmark for future litigation concerning the impact of social media on youth mental health.