LOS ANGELES—On the most anticipated day yet of a landmark social media addiction trial that began Feb. 9, Meta CEO Mark Zuckerberg took the stand at the Los Angeles Superior Court on Feb. 18 to answer allegations that he engineered his social media platforms to be addictive to children despite knowing the potential harms.

Plaintiff’s attorney Mark Lanier wasted no time setting the moral tone, opening with the suggestion that there are different ways to deal with vulnerable people—help them, ignore them, or “prey upon them.”

At the center of the case is a 19-year-old California woman identified in court documents by the initials “K.G.M.” or “Kelsey G.M,” who is accusing tech giants of engineering products that rewire young people’s brains and trap them in a cycle of addiction and mental illness.

The complaint alleges the plaintiff became addicted to Instagram as a child and suffered resulting harms, including depression, anxiety, and body dysmorphia.

Hers is one of a handful of bellwether trials that will presage how thousands of related cases brought by children, parents, school districts, and state attorneys general are argued and tried—and what kind of damages might be expected.

Like Big Tobacco and national opioid settlements before them, these cases mark a generational turning point and could have profound long-term impacts on how the industry operates.

Grilling the CEO

At the heart of the plaintiff’s strategy is a comparison of Zuckerberg’s previous statements—including those made under oath in congressional testimony—to a cache of thousands of pages of internal company documents, emails, and message chains, recently unsealed.

In a courtroom packed with media, lawyers, and grieving parents who say their kids’ deaths were instigated by Meta’s apps, Lanier grilled the CEO on statements he made related to Instagram age restrictions; whether the company has sought to drive user time on its apps, including among children; and scientific consensus on links between social media usage and youth mental health harms.

Zuckerberg stuck to a library of stock responses, mostly reiterating his “north star” was to create a product that provides value to users, with the amount of time they choose to spend on a given app being a fortuitous byproduct.

“I think if people use something in the near-term but aren’t happy with what they’re doing ... or using it more than they want to, I don’t think it’s good for us in the long term,” Zuckerberg said.

The company has evolved policies and features over time to respond to concerns in a way that balances different stakeholder interests—users, free speech advocates, and those concerned with problematic use, including among children—according to Zuckerberg.

A rare moment of levity arrived when Lanier asked him if he’d had lots of media training.

“I don’t know,” Zuckerberg mused. “I think I’m actually sort of well-known to be very bad at this.”

Testifying before Congress in 2024, Zuckerberg said that he did not give his Instagram teams goals “around increasing the amount of time people spend,” and that children under 13 were not allowed on the app.

He also testified to Congress, and reiterated on Feb. 18, that he didn’t believe the current scientific literature supported claims of a link between social media use and increased mental health harms among young people.

That was contradicted last week by a star witness for the plaintiff, Stanford psychiatrist Dr. Anna Lembke, who reported social media addiction cases are skyrocketing among young users, and detailed the ways in which app features are designed to exploit vulnerabilities in their developing brains.

In a cascade of internal slide presentations, reports, emails, and text chains, Lanier showed where insiders at Meta revealed that they viewed the algorithm as “absolutely tuned to maximize engagement in a maximally principle-less way” and were squarely focused on increasing time spent on its apps, including among teens and children under age 13.

“When Kaley is 10 years old and she’s on Instagram, at that time you were trying to set goals to drive ’time spent,' weren’t you?” Lanier charged.

Plaintiffs claim that Meta and other platforms intentionally designed features to hook young people and keep them consuming content, even when they don’t want to.

Zuckerberg clarified that the company had long since abandoned setting goals for its teams to simply increase “time spent” on its apps, opting instead for a focus on “creating value” that would keep users engaged over the long-term.

“At some point, I decided I didn’t want the teams to have specific goals around time,” he said. “The basic assumption I have is that if something is valuable, people will do it more.” He said that was different from setting a goal for employees to encourage people to spend time on the app.

Most internal documents showing a focus on “time spent” dated from 2017 or 2018. But in a 2022 performance review, Instagram head Adam Mosseri said his primary goal was to ensure the app remained culturally relevant, “as measured by time, and sharing, particularly with teens.”

In the cut-throat, fast-moving tech world, Zuckerberg explained, there are few metrics by which a company can measure its progress against competitors, and time spent is one of them.

Teens and Tweens

In more than one email exchange, employees noted Zuckerberg had “decided our top priority for the company in 2017 is teens.”

In a chat, employees wrote, “Oh good, we’re going after 13-year-olds now?” Others responded, “Yeah, Zuck has been talking about it for awhile,” and “It was gross the last time he mentioned it.”

On cross examination, attorneys for the defendant suggested such references were only to potential products, now abandoned, that would be specifically designed for children under 13.

“I think in general there are a meaningful number of people who lie about their age in order to use the services,” Zuckerberg said, noting a “bunch of systems” the company has evolved over time to try to identify and remove underage users.

A 2018 market analysis presentation shared internally noted tweens had the highest retention of any age group in the country, with people who joined Facebook at 11 years old having nearly four times the long-term retention as those who joined as 20-year-olds, and that teen adoption on Instagram had grown more rapidly year after year.

“If we want to win big with teens, we must bring them in as tweens,” the presentation suggested.

Zuckerberg said the document was misconstrued and might refer to attempts to build services specifically for users under 13.

Teen use, he said, accounts for less than 1 percent of revenue.

Answering charges on internal documents, including a study Facebook commissioned from the University of Chicago suggesting that beauty filters cause mental health harms to teenage girls, Zuckerberg said he attempted to strike a balance of free expression and safety.

“I felt like it would be going too far to tell people they couldn’t make them,” he said, later noting Meta never created its own filters to mimic cosmetic surgery.

While temporarily banning filters that could not be replicated with makeup, Meta ultimately opted to allow users to create and use them, but stopped short of recommending the features. The company banned filters that mimic or promote cosmetic surgery. 

The witness also cited a report from the National Academy of Sciences that found no evidence to support a causal link between social media use and negative mental health impacts for young people.

In a coda to his examination of the tech titan, Lanier unfurled a mosaic of K.G.M.’s Instagram photos, printed on a scroll of canvas that stretched approximately 30 feet, snaking around the inner well of the courthouse.

Zuckerberg owns around 13 percent of the company; his share is currently valued at around $215 billion.

Asked about his economic motives, the CEO noted he has pledged to give away the vast majority of his wealth, and already gives billions to scientific research. The more valuable the company, he reasoned, the more money he can give to such causes.

“Have you pledged any of your money to help the victims of social media?” Lanier asked.

Zuckerberg said he disagreed with the characterization of the question.