Los Angeles: Mark Zuckerberg will take the stand Wednesday in a closely watched California trial examining whether social media platforms were deliberately designed to addict young users. This is the first time the Meta chief will defend the safety of his platforms directly before a jury.

The 41-year-old executive, who leads Meta Platform, parent company of Facebook, Instagram and WhatsApp is the most anticipated witness in a Los Angeles courtroom where jurors are weighing whether tech giants bear responsibility for mental health harms allegedly linked to compulsive social media use.

Background of the case

The case centers on claims brought by a now 20-year-old California woman who began using YouTube at age six and Instagram at 11, later joining TikTok and Snapchat. Her lawyers argue that the platforms were intentionally engineered with algorithms and design features aimed at maximizing engagement among minors, contributing to depression, anxiety and eating disorders.

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The trial is the first in a series of cases that could shape how thousands of similar lawsuits against social media companies are resolved nationwide. Proceedings are focused narrowly on app design, recommendation algorithms and personalization tools, as federal law largely shields platforms from liability for user-generated content.

Meta’s legal team sought during jury selection to exclude potential jurors viewed as overly hostile toward Zuckerberg, whose public image has long drawn scrutiny.

What did Adam Mosseri say?

Earlier this month, Instagram chief Adam Mosseri testified that he rejects the label of “addiction,” instead describing heavy engagement as “problematic use.” Comparing it to binge-watching television, Mosseri said he did not consider such behavior equivalent to clinical addiction.

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Plaintiff attorneys also called psychiatrist Anna Lembke, who told jurors that social media can function as a “gateway drug” for young users by reshaping developing brains and reinforcing compulsive behaviors.

Internal company communications introduced in court showed debate among Meta executives over features such as cosmetic surgery filters. Critics inside the company had warned of potential harm to teenage girls, while others argued removing the filters could weaken Instagram’s competitive position against TikTok.

While TikTok and Snapchat were initially named in the complaint, both companies reached confidential settlements before trial. Lawyers had also planned to call Neal Mohan, chief executive of YouTube, but said this week they would instead question another company executive.

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The Los Angeles trial runs alongside a broader federal case in Oakland that could head to trial in 2026. Separately, Meta faces legal action in New Mexico, where prosecutors allege the company prioritized profits over protecting minors from online predators.