Parents say teens are addicted to social media. Now, a jury will decide.

For years, parents alleged that top social media companies had gotten teens hooked on their products with addictive design features, arguing in legal filings these choices led to depression, anxiety, eating disorders–and in some tragic circumstances–death.

These stories helped spur a sweeping regulatory movement that led states and governments around the world to pass laws restricting teens’ use of social media and forced tech companies to take bolder actions to protect young people.

Now, those concerned parents will make their argument in court this week when the first of several high-profile social media addiction lawsuits against Meta, TikTok and YouTube goes to trial. These suits will test the proposition of whether social media causes psychological harm, which could have profound implications for the industry along with ordinary consumers.

The first bellwether case representing families and social media victims, which will appear in Los Angeles County Superior Court, focuses on a teen girl who says she suffered from anxiety and depression after she used various social media platforms throughout her childhood.

Since 2022, school districts, dozens of state attorneys general and other families have filed a deluge of lawsuits against big tech platforms–many of which have been consolidated into a separate case before U.S. District Court for the Northern District of California. Many of the cases accuse the technology industry of designing algorithms to keep teens scrolling, viewing and checking their social media, maximizing profits while fueling a youth mental health crisis. Instead of warning the public about the dangers of their products, the lawsuits charge, tech companies downplayed what they knew about the harmful effects of their platforms.

Tech companies dispute those claims, arguing families are complaining about the effect of content made by users, for which the companies are not legally responsible. They also argue that they offer ways for people to protect themselves from undesirable experiences, including a suite of youth safety tools. In some cases, lawyers for the industry also argue in court filings that the victims’ injuries might instead be the result of outside factors, including complex family and school circumstances.

The trial will put the spotlight on an emerging debate within the mental health field about the connection between social media and climbing teen rates of depression, anxiety and suicide ideation. The Biden and Trump administrations have argued that social media is exacerbating mental health issues among adolescents. But a 2023 report by the American Psychological Association found that social media use “is not inherently beneficial or harmful to young people” and called for more research.

“It’s a complex issue. Research doesn’t show that all digital media use is bad or addictive,” said Tamar Mendelson, a professor at Johns Hopkins Bloomberg School of Public Health, who added that there was no official psychiatric diagnosis of social media addiction.

One study “actually shows that the kids who seem to have the most mental health problems were actually ones who used almost no digital media, as well as the ones who used it excessively,” she added. “There seemed to be sort of a medium point of use where teens were actually the most mentally healthy.”

YouTube spokesman José Castañeda denied the families’ allegations, saying that the company worked with youth and mental health experts to build “services and policies to provide young people with age-appropriate experiences, and parents with robust controls.”

Meta spokeswoman Liza Crenshaw also denied the allegations in a statement, arguing the company has introduced “meaningful changes” to its platform, including offering “Teen Accounts with built-in protections and providing parents with tools to manage their teens’ experiences.” Representatives for TikTok didn’t respond to requests for comment.

Eric Goldman, who is associate dean for research at Santa Clara University School of Law and has studied internet regulations, said it might also be difficult to prove legally whether it’s the internet platforms that are causing the mental distress teens are experiencing.

“Assuming that there is this thing called addiction that’s legally recognized, who causes that addiction?” he asked. “How do we measure the causal components of that?”

Still, if the legal movement against the tech companies is successful, the verdicts could prompt tech companies to change the design of their social media platforms or expand the legal liability for potential harms their users experience. Social media victims could also recoup lucrative monetary awards for the harms they experienced.

Jury selection is scheduled to begin Tuesday for the consolidated case representing social media victim families before California Superior Court Judge Carolyn Kuhl. The case focuses on the claims of K.G.M., a 19-year old whom the court is allowing to testify anonymously. As a minor, she used all four social media platforms but said she later became addicted and suffered from anxiety, depression, self-harm and suicidality, according to legal filings.

“She is going to be able to explain in a very real sense what social media did to her over the course of her life and how in so many ways it robbed her of her childhood and her adolescence,” Matthew Bergman, founder of the Social Media Victims Law Center who is representing K.G.M. and other victims in the suits, said during a media briefing last week.

“She is very typical of so many children in the United States–the harms that they’ve sustained and the way their lives have been altered by the deliberate design decisions of the social media companies.”

In court filings, Google has challenged that narrative, alleging K.G.M. experienced difficult family relationships, abuse and bullying at school, which played a role in her mental health struggles.

Trials for school districts, who allege they have been forced to address the harms to kids caused by social media, are expected to be start being heard this summer by U.S. District Judge Yvonne Gonzalez Rogers. She is also expected to hear cases brought by dozens of state attorneys general against Meta arguing the company violated consumer protection laws because they were deceptive about the safety of their products.

The cases echo lawsuits brought by states in the 1990s against tobacco companies that successfully alleged the industry targeted young people, knowingly covered up the risks of cigarettes and contributed to public health problems that strained the health system.

To bolster that point, the lawsuits often point to how the companies use subtle product design such as “infinite scroll,” which delivers an endless stream of content, “autoplay,” which automatically plays the next video, notifications and “like” counts to keep young people engaged on their services.

Unlike with tobacco, however, experts say the plaintiffs might face a challenge in proving those features cause addiction. A lot of the academic literature about the potential harms of social media for teens demonstrates a correlation link between internet use and mental health struggles and not causation, said Mendelson, the Johns Hopkins professor.

But the families suing tech companies are banking on the companies’ internal research to demonstrate the extreme steps platforms took to attract teens, how they tracked how much time they spent there, and what they knew about the effect of their services on adolescents’ mental health.

One legal filing alleges Meta researchers designed a study–an effort code-named “Project Mercury”–in which people were asked to randomly stop using Facebook and Instagram for a month compared to a control group. The group that stopped using Facebook for a week reported lower feelings of depression, anxiety, loneliness and social comparison but the company halted the research project, arguing the results were biased because of an existing media narrative, according to the lawsuit. Crenshaw, of Meta, said the study confirmed an expectation effect, where people who reported a reduction in bad feelings already thought Facebook was bad for them.

“Internal documents that have been held establishing the willful misconduct of these companies are going to–for the first time–be given a public airing,” Bergman said. “The public is going to know for the first time what social media companies have done to prioritize their profits over the safety of our kids.”