The 20-year-old plaintiff at the center of a landmark social media trial is set to testify in court on Wednesday.
The lawsuit, brought by a woman identified as "Kaley," alleges major social media companies intentionally designed their platforms to be addicting.
The lawsuit claims Kaley was exposed to those addictive design features as a child and got hooked on social media apps starting as young as age 6. The suit specifically claims features like auto-scrolling got Kaley addicted to the platforms, ultimately leading to anxiety, depression and body image issues.
The case is being heard in the California Superior Court of Los Angeles County, with Meta -- Facebook and Instagram's parent company -- and YouTube, which is owned by Google, moving forward as defendants.
Social platforms Snapchat and TikTok were previously named in the lawsuit but reached settlements with the plaintiffs last month without admitting wrongdoing.
The social media companies deny the allegations. They have argued that other factors contribute to the mental health of young social media users and that they have put in place guardrails to protect them, including specific parental controls for accounts belonging to children and teens.
Facebook founder and Meta CEO Mark Zuckerberg testified in the trial last week, answering questions related to age restrictions, app engagement and filters.
Instagram head Adam Mosseri gave testimony earlier in the trial and said he disagreed with the term "addiction" as used in the lawsuit. He said "clinical addiction" is different from "problematic use" of Instagram, which he said was "real" and described the latter as users spending "too much time" on the platform.
Mosseri said there is always a tradeoff between "safety and speech," saying users don't like it when they remove options from Instagram.
The case is the first of more than 1,500 similar lawsuits nationwide to go before a jury, potentially setting a precedent for how tech companies are held liable for product design.
In a previous statement to ABC News, a Meta spokesperson said, "We strongly disagree with these allegations and are confident the evidence will show our longstanding commitment to supporting young people."
Meta said that the company has made "meaningful changes" to its services, such as introducing accounts specifically for teenage users.
In a separate statement to ABC News, a Meta spokesperson added, "The question for the jury in Los Angeles is whether Instagram was a substantial factor in the plaintiff's mental health struggles. The evidence will show she faced many significant, difficult challenges well before she ever used social media."
YouTube has also said the allegations in the lawsuit are "not true."
"Providing young people with a safer, healthier experience has always been core to our work," spokesperson José Castañeda said in a previous statement to ABC News. "In collaboration with youth, mental health and parenting experts, we built services and policies to provide young people with age-appropriate experiences, and parents with robust controls."
