A jury in Los Angeles found ‌Google and Meta liable for a woman's social media addiction in a landmark social media lawsuit.

The jury found that Instagram, which is owned by Meta, and YouTube, which is owned by Google, were responsible for harm caused to the anonymous plaintiff - awarding her $6 million in damages.

It's seen as a bellweather decision that will inform hundreds more cases against social media firms for creating addictive algorithms.

Meta said it "respectfully disagrees" with the verdict and will appeal, while Google said: "We disagree with the verdict and plan to appeal."

After more than 40 hours of deliberation across nine days, California jurors decided Meta and YouTube were negligent in the design or operation of their platforms.

The jury also decided each company's negligence was a substantial factor in causing harm to the plaintiff.

The trial, which lasted around a month and ended on Wednesday when the verdict was delivered, centred around arguments that Instagram and YouTube (and TikTok and Snapchat but they settled out of court) were built to be addictive and were therefore harmful.

It focused on the case of KGM, or Kaley, as she was called in court, a now 20-year-old Californian who says she developed a number of mental health issues after using social media from a young age.

"How do you make a child never put down the phone? That's called the engineering of addiction," her lawyer, Mark Lanier, told the jury.

"They engineered it, they put these features on the phones. These are Trojan horses: They look wonderful and great...but you invite them in and they take over."

The trial saw Meta chief executive Mark Zuckerberg take the stand in front of a jury for the first time.

During his testimony, the tech billionaire insisted that he built his platforms "to have a positive impact in people's lives".

"It's very important to me that what we do [...] is a positive force in their lives," he told the jury.

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Instagram boss Adam Mosseri was also called into court and told the jury there was no scientific evidence that social media was addictive.

He said it was important to differentiate between clinical addiction and what he, and others at Instagram, describe as "problematic use".

When asked about the plaintiff spending 16 hours in one day on Instagram, he told the court: "That sounds like problematic use."

YouTube largely contested any claims it should be in court in the first place, arguing it doesn't count as social media and there was almost no suggestion in the evidence presented to court that the plaintiff was addicted to the platform.

YouTube's lawyer Luis Li noted that the plaintiff said she lost interest in YouTube as she grew older.

"Ask whether anybody suffering from addiction could just say, 'Yeah, I kinda lost interest,'" Mr Li said in his closing statement. "What's your common sense tell you about that?"

Meta argued that the plaintiff's mental health difficulties had come from a troubled childhood and that "not one of her therapists identified social media as the cause" of her problems.

The trial is the first in a series of landmark cases against Instagram, YouTube, TikTok and Snap that are set to follow in the US.

More than 1,600 plaintiffs, including over 350 families and over 250 school districts, accuse the companies of designing addictive products that have harmed young users.

Matthew Bergman, the founding attorney of the Social Media Victims Law Center, is representing more than 1,000 plaintiffs in the proceedings and told reporters before the verdict that simply taking the case to trial was a win in itself, according to Sky's partner newsroom NBC.

"Win or lose the outcome of this trial, victims in the United States have won because now we know that social media companies can and will be held accountable before a fair and impartial jury," he said.

"And in some cases, plaintiffs will prevail, and in some they may not, but we are just gratified for the opportunity to get this far, and there will be many more trials in the future."

(c) Sky News 2026: Social media giants found liable for social media addiction in landmark court case