A Los Angeles jury delivered a landmark verdict on Wednesday, finding Meta Platforms and Alphabet's YouTube negligent for designing addictive features that harmed a young woman's mental health.

The plaintiff, identified in court documents as K.G.M. or Kaley, a 20-year-old from Chico, California, testified that her excessive use of Instagram and YouTube beginning in childhood led to depression, anxiety, body dysmorphia, and suicidal thoughts. She started watching YouTube at age 6 and joined Instagram around age 11, spending hours daily on features like infinite scrolls, autoplay videos, and notifications that kept her engaged.

After more than five weeks of trial before Judge Carolyn B. Kuhl in Los Angeles Superior Court, the jury of five men and seven women deliberated nearly 44 hours over nine days. They determined that both companies' platforms were a substantial factor in the plaintiff's harms due to defective design and failure to warn users of risks. Meta was assigned 70% responsibility, and YouTube 30%, resulting in $3 million in compensatory damages. The jury also found evidence of malice, oppression, or fraud, paving the way for punitive damages in a separate hearing.

Lawyers for the plaintiff presented internal documents showing Meta's awareness of youth harms, including one noting that 11-year-olds were four times as likely to return to Instagram repeatedly. They likened the platforms to "digital casinos" engineered for addiction. Mark Lanier, the lead attorney, stated during opening arguments: "How do you make a child never put down the phone? That's called the engineering of addiction." Co-lead counsel Joseph VanZandt called the verdict "a referendum to an entire industry that accountability has arrived."

Meta and Google disputed causation, pointing to the plaintiff's difficult home life, including abuse, and a lack of documentation linking social media to her issues in therapy records. Meta CEO Mark Zuckerberg testified, defending features like beauty filters as supporting free expression. A Meta spokesperson said the company disagrees with the verdict and is evaluating options, while Google's José Castañeda announced plans to appeal, calling YouTube "a responsibly built streaming platform, not a social media site."

TikTok and Snapchat settled with the plaintiff before trial, with terms undisclosed. This case, the first to reach a jury on social media addiction claims, serves as a bellwether for roughly 2,000 similar lawsuits from families and school districts alleging harms to minors. It sidestepped Section 230 protections by focusing on product design rather than user content.

The ruling follows a New Mexico jury's decision Tuesday ordering Meta to pay $375 million for failing to protect children from predators on its platforms. Legal experts anticipate the verdicts could spur platform changes, such as stronger safeguards for minors, amid growing state laws restricting youth access.