The Chief Executive Officer of Meta Platforms, Mark Zuckerberg, defended his company’s policies on Wednesday during a high-profile trial in Los Angeles over allegations of youth social media addiction.

The testimony occurred in a case brought by a California woman who claims Instagram and Google’s YouTube harmed her mental health after she began using the platforms as a child.

Meta and Google have rejected the allegations and emphasized steps taken to improve user safety.

Representing the plaintiff, attorney Mark Lanier questioned Zuckerberg about his 2024 congressional testimony that users under 13 are barred from Meta’s platforms, while presenting internal company materials during cross-examination.

“If we want to win big with teens, we must bring them in as tweens,” read one internal Instagram presentation from 2018.

“And yet you say that we would never do that,” said Lanier.

Zuckerberg replied that Lanier was “mischaracterising what I am saying.” The CEO said Meta has “had different conversations over time to try to build different versions of services that kids can safely use.”

For example, he said Meta discussed creating a version of Instagram for children under 13, but ultimately never did.

The case forms part of a larger wave of U.S. litigation against social media companies regarding their effects on young users.

Meta’s competitors Snap Inc. and TikTok reached settlements with the plaintiff before the trial began.

During the proceedings, jurors viewed internal emails, including one from former Meta executive Nick Clegg, who wrote to Zuckerberg and other leaders that “we have age limits which are unenforced (unenforceable?)” and observed that differing policies between Instagram and Facebook made it “difficult to claim we are doing all we can.”

Zuckerberg responded in the email that verifying users’ ages is challenging for app developers and suggested that responsibility should lie with mobile device manufacturers.

He testified that teenagers account for less than 1% of Instagram’s revenue.

Zuckerberg was also questioned about his prior statements to Congress in 2021, when he said he had not directed Instagram teams to maximize time spent on the app.

Lanier presented emails from 2014 and 2015 in which Zuckerberg outlined objectives to increase user engagement by double-digit percentages.

Zuckerberg said the company’s approach has since evolved.

“If you are trying to say my testimony was not accurate, I strongly disagree with that,” Zuckerberg said.

Jurors were shown a 2022 document listing future “milestones” for Instagram, including plans to raise average daily usage from 40 minutes in 2023 to 46 minutes in 2026.

The milestones are not “goals,” Zuckerberg said, but a “gut check” for senior management about how the company is doing.

In response to questioning by Meta’s lawyer, Paul Schmidt, Zuckerberg said that Meta bases employee goals for its products on giving users a good experience.

“If we do that well, people find the services more valuable and one side effect is they will use the services more,” he said.

This marked the billionaire Facebook founder’s first time testifying in court regarding Instagram’s impact on the mental health of young users.

Outside the courthouse, attorney Matthew Bergman, who represents other families alleging social media contributed to their children’s deaths, said parents attending the trial hope the litigation will drive change in the industry.

“We know that simply because we have achieved this milestone, justice has been done,” he said of Zuckerberg’s testimony and the trial.

The lawsuit is considered a bellwether for thousands of similar cases filed by families, school districts, and states against Meta, Google, Snap, and TikTok.

Plaintiffs argue the companies contributed to a youth mental health crisis.

A ruling against the firms could weaken longstanding legal protections shielding technology companies from liability over user-generated content decisions.

Unlike earlier cases, the current litigation focuses on platform design and operational decisions.

Past investigative reports have cited internal Meta research indicating awareness of potential mental health risks, including findings that some teens felt worse about their bodies after using Instagram and were exposed to more “eating disorder adjacent content.”

Adam Mosseri, head of Instagram, testified last week that he was unaware of a recent internal study showing no connection between parental supervision and teens’ attentiveness to their social media habits.

Trial documents also indicated that teens facing challenging life circumstances more frequently reported habitual or unintentional use of Instagram.

Meta’s legal team told jurors that the plaintiff’s medical records reflect longstanding personal difficulties and argued that social media served as a creative outlet rather than the cause of her struggles.

The U.S. cases are unfolding amid a broader international reassessment of social media’s impact on youth.

Australia has banned access to social media for users under 16, while other nations are considering similar restrictions.

In the United States, Florida has enacted a law prohibiting platforms from allowing users under 14, though industry trade groups are challenging the measure in court.