Jury selection got under way on Wednesday in Los Angeles in a trial against Meta and Snap, in which two plaintiffs argue the companies' platforms were designed to be addictive. The case is the latest in a series of legal challenges focused on how social media affects young people.

The plaintiffs filed suit in 2023. They allege that features such as endless scrolling and Snapstreaks kept them hooked and harmed their mental health.

One plaintiff is a 16-year-old from Illinois identified in court documents as S.J. The teen began using Snapchat as a young child and says the app's features led to compulsive use. According to the claims, this contributed to depression, reduced sleep, anxiety, an eating disorder, suicidal ideation and self-harm. The other plaintiff, an 18-year-old from Mississippi identified as K.D.B., says her use of Meta's platforms and Snapchat from a young age also contributed to mental health problems and self-harm.

In their complaint, filed in a Los Angeles trial court, the plaintiffs' lawyers argued that the defendants "defectively designed the platforms to specifically appeal to and addict minors and young adults, who were particularly unable to appreciate the risks posed by the platforms, and particularly susceptible to harms from those products."

TikTok and Alphabet's YouTube were part of the original lawsuit but settled before trial. Meta, which owns Facebook and Instagram, has also settled with S.J. It continues to contest the allegations made by K.D.B. A Meta spokesperson said a young person's mental health is shaped by many factors. The spokesperson added that the plaintiff "used TikTok far more than Instagram or Facebook, and her personal circumstances were a substantial factor in her struggles."

Snap, the parent company of Snapchat, also disputes the claims. A spokesperson said the company has built safeguards, safety tools and educational resources into the platform. The spokesperson said Snap believes the evidence will show it has put its community first and that the allegations misrepresent the plaintiffs' experiences and the platform's design. Both companies are expected to argue that other factors, not their products, caused the plaintiffs' difficulties.

The plaintiffs are seeking unspecified compensatory and punitive damages. Mark Lanier, founder of The Lanier Law Firm and lead counsel for the plaintiffs, said this will be the first case against Snapchat and the first time the public can see some of the company's documents.

Instagram head Adam Mosseri, Meta CEO Mark Zuckerberg and Snap CEO Evan Spiegel are all expected to testify. The plaintiffs' lawyers say the trial will likely last until mid-December. Opening statements are scheduled for early November, with Judge Carolyn Kuhl presiding. Earlier this week, Meta and Snap asked the court to split the matter into two separate trials, and according to a person familiar with the matter, Kuhl has not yet ruled on that request.

The case was chosen as one of several bellwether cases among a large number of similar claims filed against social media companies in recent years. It could heighten scrutiny of the platforms at a time when many people are already wary of the technology's effect on young people. A 2024 Pew Research Center survey of U.S. teens ages 13 to 17 found that nearly half said they are online almost constantly. In a separate landmark case earlier this year, a jury ordered companies to pay $6 million after finding they were responsible for creating products that led to harmful and addictive behavior among young users.