HOUSTON, United States

A jury in the US state of California found Meta and YouTube liable Wednesday for creating social media products that led to harmful and addictive behavior by young users in a landmark decision that could set a legal precedent for future lawsuits, according to media reports.

The Los Angeles jury voted to award $3 million in damages to the lead plaintiff in the case, a woman named Kaley, who was identified in court filings by her initials KGM.

Kaley alleged that using Instagram and YouTube from a young age in grade school led to addictive use of the popular social media platforms that contributed to her mental health problems, including depression, suicidal thoughs and body dysmorphia, where she was always worried about flaws in her appearance.

During her testimony, Kaley, now 20, described spending all day on social media and getting an emotional "rush" from likes and notifications, keeping her glued to her phone.

Her attorneys called the social media platforms "a gateway" to her addiction.

The jury's decision caps a weeks-long trial that put Meta CEO Mark Zuckerberg and Instagram chief Adam Mosseri on the stand to defend their products in a case that drew comparisons to the tobacco industry lawsuits in the 1990s.

Kaley brought the case against Meta, which owns Instagram and Facebook, and Google-owned YouTube in 2023. TikTok and Snapchat’s parent, Snap, were named in the original suit, but settled out of court before the trial began in late January.

Throughout the trial, Kaley's attorney, Mark Lanier, argued that Meta and YouTube were aware that their social media products harmed children, but continued to prioritize profits above safety.

The jury concurred, finding Meta and YouTube liable for the two main allegations in this case: negligence and failure to warn users of the potential health risks from using the platforms.

Legal experts said social media companies have long used a clause in the law called Section 230 that prevents internet companies from liability for third-party content posted on the platforms, to avoid legal action. But Kaley's case centered around how the apps are designed, not the content.

During the trial, Meta and YouTube denied that Kaley's use of social media led to her mental health issues, arguing that her family history, difficulties at home and school, and learning disabilities played a more significant role in her psychological and emotional struggles.

"We respectfully disagree with the verdict and are evaluating our legal options," a Meta spokesperson told CBS News.

Google did not immediately comment on the decision, but both companies are expected to file an appeal.

Experts believe Wednesday's decision will likely set a legal precedent that will transform the debate about social media addiction and scrutinize what role apps may play in the engineering of addictive user habits, and whether individuals, like Kaley, can prove they are afflicted by apps.