YouTube is also named in the suit, while Snapchat and TikTok both reached settlements ahead of the trial.
One of the top executives at Meta, which also owns Facebook and WhatsApp, Mosseri is expected to be questioned in court all day on Wednesday.
Early on in his testimony, he agreed on a broad point made by Mark Lanier, the lead attorney for K.G.M, that Instagram should do everything within its power to help keep users safe on the platform, especially young people.
However, Mosseri said he did not think it was possible to say how much Instagram use was too much.
Whether use was a problem was “a personal thing,” Mosseri said, explaining that one person could use Instagram “more than you and feel good about it.”
“It’s important to differentiate between clinical addiction and problematic use,” he added.
“I’m sure I’ve said that I’ve been addicted to a Netflix show when I binged it really late one night, but I don’t think it’s the same thing as clinical addiction.”
Yet, Mosseri repeatedly said he was not an expert in addiction in response to Lanier’s questioning.
Lanier brought up with Mosseri an internal Meta survey in which the company asked 269,000 Instagram users about their experiences using the app and found 60% had seen or experienced bullying in the previous week.
The lawyer added that K.G.M had made over 300 reports to Instagram about bullying on the platform, asking whether Mosseri had been aware of that fact.
Mosseri said he had not known.
Lanier asked Mosseri what he thought of K.G.M’s longest single day of use of Instagram being 16 hours.
“That sounds like problematic use,” the Instagram boss answered. He did not call it an addiction.
Mosseri was also asked about a 2019 email exchange between Meta executives, in which they discussed the potential negative impact for users caused by a feature allowing people to change their physical appearance in photos.
Nick Clegg, who worked as Meta’s head of global affairs for several years after more than a decade as a Member of Parliament, was among those to raise concern about the image filters.
He said Meta would end up “rightly accused of putting growth over responsibility,” which would ultimately have a “regressive” impact on the company’s reputation.
Mosseri said the firm ultimately decided to ban image filters that went beyond mimicking the effects of makeup.
After Lanier challenged that claim, Mosseri admitted that the ban on such filters had been “modified”, while denying it had been lifted completely.
