Meta CEO Mark Zuckerberg entered a downtown Los Angeles courthouse in largely the same way as all the attorneys, reporters, and advocates who’d come to watch his landmark trial testimony, but with one notable difference: he was flanked by an entourage that appeared to be wearing Meta’s Ray-Ban smart glasses. To get to the courtroom, he walked past a crowd of parents whose children died after struggling with issues they attribute to the design of social media platforms including those that Meta makes. He would spend the next eight hours often answering questions in his signature matter-of-fact (or less charitably, monotone) cadence, denying his platform was liable for the harms.

Zuckerberg was questioned through the morning session by Mark Lanier, the lead litigator for plaintiff K.G.M. She’s a 20-year-old woman who claims Meta and Google’s design features encouraged her to compulsively use their apps and led to mental health issues, which the companies generally deny. Lanier’s charismatic style, drawing from his other profession as a pastor, was in stark contrast to Zuckerberg’s responses on the witness stand, where he tried to inject nuance into how employees discussed — and sometimes criticized — various safety decisions. At times, Zuckerberg pushed back on Lanier’s characterization of his testimony. “That’s not what I’m saying at all,” he said at one point, according to NPR. Meanwhile, the judge admonished people in the courtroom not to wear Meta’s AI glasses, and that they could be held in contempt of court if they fail to delete any recordings; parents whose children died after experiencing harms they attribute to his platform watched on.

During his time on the stand, Zuckerberg was pressed on both his decisions at Meta and previous public statements. He was asked about alleged contradictions between prior claims that he’d tried to keep kids under 13 from Facebook and Instagram and documents describing the value of getting users on the platforms young. He was also asked to address decisions he had made that would impact young users of his platform, such as his decision to forgo a permanent ban on AR filters that alter users’ faces in ways that simulate cosmetic surgery.

Zuckerberg’s answer to the AR filter question helped illustrate one of his go-to strategies: arguing that Meta had made careful decisions to balance free expression against potential harms. During the testimony, Zuckerberg addressed a discussion among Meta executives in 2019 about whether to lift a temporary ban on the filters, which Instagram chief Adam Mosseri was asked about last week. Zuckerberg testified that after reviewing research on the filters’ impact on user wellbeing, he felt that the available evidence of their harm was not compelling enough to justify the tradeoff to limiting a form of speech on the platform. “On some level you don’t really build social media apps unless you care about people being able to express themselves,” Zuckerberg said. “I think we need to be careful about when we say, ‘hey there’s a restriction on what people can say or express themselves.’ I think we need to have quite clear evidence that thing would be bad.”

Zuckerberg ultimately decided to allow creators to make some of the filters, with the exception of things like mimicking nip and tuck lines, but not to recommend them or for Instagram to make them itself.

Lanier suggested that Meta prioritized increasing users’ time spent on the platform rather than wellbeing, but — as he’s long done in other settings — Zuckerberg insisted that Meta has intentionally shifted its internal messaging to focus on increasing product value for users, even if it leads to short-term decline in usage. While some documents showed that employees considered how banning the filters could discourage some users, Zuckerberg said that wasn’t a big factor in his decision since they weren’t hugely popular tools in the first place.

Still, Zuckerberg acknowledged that not everyone on his team agreed with the decision. “You had a set of people who think about wellbeing issues who had some concern that there might be an issue, but weren’t able to show any data that I found compelling that there was enough of an issue to be worth restricting people’s expression,” he said. Lanier showed him an email from another Meta executive who said she respected Zuckerberg’s call, but didn’t agree with it based on the risks and her personal experience with a daughter who experienced body dysmorphia. “There won’t be hard data to prove causal harm for many years,” the executive said.

When Zuckerberg reiterated he didn’t find the available research compelling enough to justify a broader ban, Lanier asked if Zuckerberg had a degree in a variety of professions. “I don’t have a college degree in anything,” Zuckerberg responded.

Zuckerberg’s full-day testimony concluded part of the second week of a trial expected to last at least six. Jurors will soon hear from former Meta employees, including those who disagreed with the company’s approach to teen safety, and executives from YouTube, which is also a defendant in the case.

Parents who watched on from the public seats told reporters that they didn’t feel they learned much new from the testimony, but many said they still felt it important to make their presence known to the CEO. “I think it’s pretty obvious who the parents in the room are, and I hope that when he looks out into that courtroom, because we’re sitting right there, that he sees that and he feels that, because the only way we’re really going to get change from him is when he’s empathetic,” said Amy Neville, whose son Alexander died from fentanyl poisoning at age 14 allegedly facilitated by Snapchat (which settled its part of the K.G.M. case). “When we can touch his empathy, we can get the change that we seek. And so hopefully, maybe we got a little bit of that today. Remains to be seen.”