Los Angeles Superior Court Judge Carolyn Kuhl denied motions for a new trial on Tuesday, according to court documents.

The ruling means a March jury verdict awarding $6 million in damages will remain in place while both companies pursue appeals.

The case was brought by a 20-year-old California woman identified in court records as K.G.M., also known as Kaley.

She told jurors she began using YouTube at the age of six and Instagram at nine, and later developed anxiety, depression, body dysmorphia and suicidal thoughts.

Her lawyers argued that features built into the platforms, including algorithmic recommendations, beauty filters, endless scrolling and push notifications, encouraged compulsive use and contributed to her mental health issues.

After hearing the evidence, the jury found both companies negligent and concluded they acted with malice, oppression and fraud.

Jurors awarded $3 million in compensatory damages and a further $3 million in punitive damages, bringing the total award to $6 million.

Meta was assigned 70% of the liability, amounting to $4.2 million, while YouTube was held responsible for the remaining 30%, or $1.8 million.

The trial attracted attention because it was the first to reach a verdict among more than 1,600 related lawsuits filed across the United States by young people, families and school districts.

The litigation accuses social media companies of designing products that encourage addiction among children and teenagers while contributing to mental health problems.

Several senior technology executives testified during the proceedings. Meta chief executive Mark Zuckerberg spent about eight hours on the witness stand and was questioned about internal company documents showing that Instagram had four million users under the age of 13 in 2015.

Instagram head Adam Mosseri also testified and acknowledged that spending 16 hours a day on the platform could be “problematic.”

Meta said it “respectfully disagrees” with the verdict and plans to appeal. The company argued that teenage mental health is influenced by many factors and cannot be linked to a single app.

Google, which owns YouTube, also intends to challenge the ruling. The company argued that the case “misunderstands YouTube” because it views the service as a streaming platform rather than a social media network.

As it stands, lawmakers and child safety advocates are currently pushing for stronger protections for young users online, including uncompromising age-verification requirements, expanded parental management and changes to platform design.

At the centre of the case is a 19-year-old woman from California, identified in court papers as K.G.M. She argues that she became hooked on the apps while still a child and that prolonged use damaged her mental health. 

She is asking the court to hold the companies liable for the effects of their product design, not just the content she consumed.

Beyond a single dispute, the trial emphasises whether a digital product can be treated like any other consumer good when it causes harm. That question will now be argued in open court, under oath, and in front of a jury.

Lawyers for the plaintiff say this is the first time technology firms must defend themselves at trial on claims that their platforms injured a young user.

Report Links Growing Mental Health Crisis among Children to Use of Technology

Matthew Bergman, the lead attorney, said: “They will be under a level of scrutiny that does not exist when you testify in front of Congress.”

The jury must decide whether the companies were negligent, and whether use of the platforms played a role in K.G.M.’s mental health challenges, as distinct from other factors in her life or the third-party material she viewed. Legal experts say the result could influence hundreds of similar cases awaiting resolution.

“This is really a test case,” said Clay Calvert, a media lawyer at the American Enterprise Institute. “We’re going to see what happens with these theories”.

Senior executives are expected to be called. Meta chief executive Mark Zuckerberg is due to testify, an uncommon sight for a technology founder in a civil courtroom. 

Snap’s chief executive Evan Spiegel had also been expected, but Snap agreed to settle the case against it earlier this month. The company has not disclosed the terms.

The remaining firms are preparing distinct defences. Meta has said its products did not cause the plaintiff’s difficulties and mental health challenges. YouTube plans to argue that its service is different in nature from platforms such as Instagram and TikTok and should not be treated the same way. TikTok has declined to outline its courtroom strategy.

Since 2022, thousands of lawsuits across the United States have accused social media companies of deliberately designing addictive features that harm children. 

In September 2025, a California court allowed expert witnesses to explain how tools such as endless scrolling, autoplay and algorithm-driven feeds affect young users’ mental health. That ruling cleared the path for this bellwether case.

At the same time, the companies are fighting a parallel issue for public trust. They have rolled out new parental controls, funded school workshops and partnered with youth groups to show they take safety seriously. Meta has sponsored “Screen Smart” sessions in schools. 

TikTok has backed parent programmes under the banner “Create with Kindness”. Google, YouTube’s parent company, has worked with the Girl Scouts on online safety badges.

Individuals say these initiatives muddy the waters. Julie Scelfo, founder of Mothers Against Media Addiction, said: “These companies are using every lever of influence that you can imagine. It can be very confusing for parents who to trust.”