Meta CEO Mark Zuckerberg was clearly getting testy.

“That’s not what I’m saying at all,” said the tech billionaire. “I think you’re misunderstanding what I’m saying,” Zuckerberg responded. “You’re mischaracterizing what I’m saying,” he shot back.

The executive was testifying on Wednesday before a jury in Los Angeles in a marquee social media trial accusing Meta of deliberately designing features of Instagram to addict children, and the legal team for the family suing was intent on showing that Zuckerberg’s fingerprints were all over the company’s big decisions.

Mark Lanier, a Texas trial lawyer and pastor with a folksy courtroom demeanor, directed Zuckerberg’s attention to a 2020 internal Meta document showing that 11-year-olds were four times as likely to keep coming back to Facebook, compared to older users. Instagram’s minimum age for signing up is 13.

“People who join Facebook at 11 years old? Lanier asked Zuckerberg. “I thought y’all didn’t have any of those?”

Lanier then went over Meta internal documents highlighting goals to increase the time 10-year-olds spend on Instagram.

“I don’t remember the context of this email from more than ten years ago,” Zuckerberg said. “I think the way we should build things is to build useful services for people to connect with their family and friends and learn about the world.”

One 2018 internal Meta document stated “If we wanna win big with teens, we must bring them in as tweens,” Lanier pointed out, saying that undercut Meta’s own policies.

The legal team representing the plaintiff, a 20-year-old California woman known in court documents as “Kaley,” attempted to demonstrate that the top-down goal of Meta has always been to encourage users to get on their platforms as young as possible, and once there, to figure out ways to keep them around. Often features like “beauty filters,” made the app more alluring, Lanier argued.

When the company hired experts who affirmed that such appearance-enhancing filters contributed to body-image issues among young girls, Zuckerberg would not dispense with the filters tools, calling getting rid of them was “paternalistic.”

Under questioning in court, the billionaire Facebook founder responded: “What we allowed was letting people use those filters if they wanted but deciding not to recommend them to people,” he said. “So that was the balance we came to to let people express themselves the way they want.”

Kaley, who’s also identified as KGM in court documents, often used these filters, which her lawsuit says contributed to body dysmorphia and other mental health issues.

Had Zuckerberg looked at Kaley’s Instagram posts before the trial, Lanier asked? His staff had shown him some, he responded.

Files are brought inside the Los Angeles Superior Court on Feb 18, 2026 as part of a major trial involving Meta and Google over whether their products harm young people.

Jill Connelly/Getty Images

hide caption

toggle caption

Jill Connelly/Getty Images

Advertisement

That’s when Lanier, who is known for orchestrating spectacles at trial, had five lawyers unspool a roughly 20-foot collage of hundreds of photos that Kaley posted to Instagram. Lanier implored Zuckerberg to dwell on the posts. Other observers in the room, including the media, were not able to see the photos.

When it was time for Meta’s lawyer to ask Zuckerberg questions, he emphasized that the company does not have an incentive for people to have harmful experiences on its services.

“From a business perspective, people think if we maximize the amount of attention people spend, that that’s good for us,” Zuckerberg said. “But if people feel like they’re not having a good experience, why would they keep using the product?”

Keeping users safe, especially teen users, has always been a priority, Zuckerberg said.

“Questions about well-being I consider part of this for sure,” he said. “If you build a community and people don’t feel safe, that’s not sustainable and eventually people go and join another community.”

1,600 other plaintiffs

The appearance of Zuckerberg, the star witness of the trial, came in the second week of what’s expected to be a six-week proceeding. Other tech executives, social media specialists, addiction experts and others have also testified.

Kaley, the plaintiff, is expected to deliver the most emotional testimony later in the trial. Her lawsuit claims she began using social media at age 6, including YouTube, Instagram, TikTok and Snap. After becoming hooked on the platforms, she said her body image issues, depression and suicidal thoughts worsened. The suit points to features like beauty filters, infinite scroll and auto-play as being tantamount to a “digital casino.” Evidence of the harms of these features were concealed from the public, the lawsuit says.

Julianna Arnold, whose daughter died from fentanyl she bought from someone on Instagram, talks about watching Mark Zuckerberg testify outside the Los Angeles Superior Court on Feb. 18, 2026.

Jill Connelly/Getty Images

hide caption

Advertisement

toggle caption

Jill Connelly/Getty Images

In response, Meta and Google, which owns YouTube, have said the accusations over-simplify the complexity of adolescent mental health issues. The companies argue social media use does not directly cause young people to be mentally unwell, so they should not be held legally liable for a user’s mental health struggles.

Kaley’s legal team called expert witnesses who described multiple studies linking regular social media use with worsening depression, anxiety and body image issues.

The jury will determine to what degree social media platforms should be held legally culpable for plaintiff Kaley’s struggles. The trial is a bellwether case tied to 1,600 similar suits filed by families and school districts. How the jury decides is expected to influence settlement talks in all those pending cases.

While debates about social media addiction have raged for decades, it has taken until now for a major trial on the issue to unfold largely due to a federal legal shield that has protected Silicon Valley. A law known as Section 230 of the 1996 Communications Decency Act has allowed tech companies to fend off lawsuits over what users post to their sites. Social media firms have also won legal battles, including a key Supreme Court case, that have found how companies curate content on platforms is a type of protected free speech.

Despite these protections, the plaintiff’s lawyers in the Los Angeles case found a way to legally attack tech giants: by treating social media apps as unsafe products, viewing Instagram, YouTube and other services as defective under product liability law. The argument is that tech companies deliberately designed social media sites as harmful and dismissed internal warnings that the services could be problematic for teenagers.

The jury will ultimately have to assess Zuckerberg’s credibility, which was under attack on Wednesday.

Lanier, Kaley’s lawyer, brought up an internal document showing how Meta communications staffers have pushed Zuckerberg to portray himself as more “human” and “relatable,” and “empathetic, and less “fake,” and “corporate,” and “cheesy.”

When questioned about his performance in various other public settings, whether in courtrooms or before Congress, Zuckerberg showed some humility.

He said: “I think I’m known to actually be pretty bad at this,” which drew some laughter from the courtroom.