A landmark trial opened this week in a California court that could reshape how the world’s largest social media platforms are judged for their impact on young users’ mental health. The case, being heard before Los Angeles Superior Court Judge Carolyn B. Kuhl and a jury, puts Meta Platforms’ Instagram and Google’s YouTube under intense scrutiny, with plaintiffs accusing the companies of deliberately designing their products to be addictive and harmful, particularly to children and teenagers.
In his opening arguments, prominent trial lawyer Mark Lanier told jurors that the lawsuit is not about isolated instances of harmful content but about the very architecture of social media platforms. Representing a young woman identified in court only as “K.G.M.”, Lanier argued that Instagram and YouTube function as “addiction machines” whose core features are engineered to capture attention, prolong use and keep users coming back compulsively. According to the plaintiff, prolonged exposure to these platforms from a young age led to severe mental health problems, including depression, anxiety and suicidal thoughts.
Lanier said his client’s experience was not an anomaly but the predictable outcome of design choices made by the companies. He argued that features such as infinite scrolling, algorithm-driven recommendations, autoplay videos and constant social feedback through likes and views were deliberately crafted to exploit psychological vulnerabilities in young users. These tools, he said, mirror techniques long used in industries such as gambling, where products are engineered to maximise engagement regardless of harm. The plaintiff’s legal team contends that internal research and company knowledge showed awareness of these risks, yet engagement and revenue growth were prioritised over user well-being.
The lawsuit places particular emphasis on the age at which users are first exposed to these platforms. K.G.M.’s lawyers told the court that she began using YouTube as a child and later became heavily engaged with Instagram during her teenage years, a period when the brain is especially susceptible to reward-seeking behaviour and social validation. The claim argues that early and sustained exposure to addictive design features disrupted her emotional development and contributed directly to her mental health struggles.
According to reports, Meta and Google have strongly denied the allegations and are expected to argue that the plaintiff’s difficulties cannot be attributed solely, or even primarily, to social media use. The companies maintain that their platforms are not designed to cause addiction and that millions of users engage with them without experiencing serious harm. They are also expected to point to a range of safety measures, parental controls and well-being tools introduced over the years, particularly for younger users. The defence is likely to argue that mental health outcomes are shaped by a complex mix of personal, familial and social factors, and that it is impossible to draw a clear causal line between platform design and an individual user’s psychological condition.
Beyond the individual claims, the trial is being closely watched because of its broader legal and regulatory implications. It is one of the first cases in the United States to test, before a jury, the argument that social media companies should be held liable for harm arising from the design of their platforms rather than from user-generated content alone. That distinction is crucial, as technology companies have long relied on legal protections that shield them from responsibility for what users post online. By focusing on product design, the plaintiffs are attempting to move the debate into the realm of consumer protection and product liability.
The case is also seen as a bellwether for dozens of similar lawsuits filed across the country by families, school districts and individuals alleging that social media platforms have contributed to a youth mental health crisis. Some companies named in related litigation have already chosen to settle, while others are watching closely to see how jurors respond to the “addiction machine” argument. A verdict in favour of the plaintiff could encourage more lawsuits, increase pressure on lawmakers to regulate platform design, and force companies to rethink features that drive engagement. A defence victory, on the other hand, could reinforce the industry’s long-standing position that social media is a neutral tool whose effects depend largely on how it is used.
The trial also feeds into a wider public debate about the role of technology in everyday life and the responsibility of powerful platforms toward their youngest users. While researchers continue to debate whether excessive social media use meets the clinical definition of addiction, there is growing concern among parents, educators and policymakers about its links to anxiety, low self-esteem and other mental health issues among adolescents. By bringing these questions into a courtroom, the case marks a significant moment in the ongoing effort to define where personal responsibility ends and corporate accountability begins in the digital age.