LOS ANGELES — A Los Angeles jury found Meta and YouTube liable for designing their platforms to be addictive in a case brought by a 20-year-old plaintiff on Wednesday. The verdict awarded $3 million in compensatory damages and $3 million in punitive damages to the plaintiff, known only as Kaley.

After nine days of deliberation, jurors agreed with Kaley on all counts. Both Meta and Google announced they would appeal the verdict.

Kaley claimed the platforms amplified her personal issues and left her with body dysmorphia, depression and suicidal thoughts. Meta's defense at trial included an argument that Kaley's family struggles and school challenges preceded her use of Instagram, which began when she was nine years old.

"It was a clean sweep with respect to liability against both Google and Meta," said Jayne Conroy, case attorney. "It will matter." Conroy added, "I bet there's a lot of math going on in boardrooms at Meta, Google, Snap and TikTok as they evaluate what that means if they know thousands of cases are coming their way."

"We will continue to defend ourselves vigorously as every case is different, and we remain confident in our record of protecting teens online," a spokesperson said in response to the verdict. "Many teens rely on digital communities to connect and find belonging."

A Meta spokesperson said reducing teen mental health to a single cause risks leaving the many broader issues teens face today unaddressed. A Google spokesperson said YouTube is a responsibly built streaming platform, not a social media site.

The case is among several upcoming bellwether trials that will test the legal theory that social media companies caused personal injuries by designing their products to be addictive in pursuit of profit. Snap Inc settled before the trial started but will be a defendant in several upcoming bellwether trials.

"Let's not draw any big conclusions," said Eric Goldman, associate dean and professor. "I don't think any of the social media services can afford to pay $6 million per injured user." Goldman said there was no guarantee the jury verdicts of the past week would stand on appeal.

In a separate case on Tuesday, a jury in New Mexico delivered a $375 million verdict against Meta after prosecutors convinced them that Meta enabled child exploitation on its platforms. State prosecutors had sought more than $2 billion in penalties in that case.