LOS ANGELES—A 20-year-old California woman at the center of a landmark tech trial took the stand for the first time Thursday in a case to determine whether social media companies engineered their products to addict young users despite known harms.

Identified in court documents as “K.G.M” or “Kaley G.M.,” the plaintiff says she became addicted to social media as a child and suffered serious harms as a result, including depression, anxiety, body dysmorphia, and suicidal ideation.

“I was on it at a young age and spent all my time on it,” Kaley told the jury. “I’d sneak it, watch in class, and anytime I tried to set limits for myself, it just didn’t work. … I couldn’t get off.”

Baby-faced, dressed in soft shades of pink that contrasted with a legion of dark-suited lawyers in the gallery, the young woman who took the stand Thursday looked every bit the shy teenager alluded to in court proceedings.

Her highly anticipated testimony, in the third week of a civil jury trial that began Feb. 9, personalized a case that has thus far centered on theoretical arguments, forensic evidence, and testimony from expert witnesses and tech executives.

“Miss G.M.,” as attorneys refer to her, is an avatar for a generation that came of age in a world in which social media was already deeply embedded—and for what plaintiffs allege is an unprecedented youth mental health crisis that has arisen as a result.

Defendants YouTube (Google) and Instagram (Meta) deny their products are designed to target young people, and more generally, that clinical social media addiction even exists.

The two tech giants, along with TikTok (ByteDance) and Snapchat (Snap, Inc.) are named in thousands of civil product liability cases—brought by children, parents, school districts, and state attorneys general—that have been consolidated into joint actions.

K.G.M’s case is one of a handful of bellwether trials—high-stakes proceedings that will determine how the others will be argued and what liability and damages may be expected.

TikTok and Snapchat settled privately before the trial began, but remain named in related cases.

‘That Rush’

Plaintiff’s attorney Mark Lanier began with a tour of Kaley’s young life, including scrapbook photos capturing favorite memories: birthday parties, a pet chihuahua, swimming, and theme parks. Happy times.

She joined YouTube at age 6. To get around the age verification, Kaley said, “I just selected a random age.” At 9, she began “sneaking” Instagram on her phone. Around the same time, she began suffering from anxiety; depression followed soon after.

By age 10, she had posted more than 200 videos to YouTube. She created an additional nine accounts to like her own posts. When she was bullied on YouTube, she continued using it “because being off of it bothered me more than the comments and the bullying,” she said.

The same went for Instagram, which at the time she joined didn’t require new users to provide date of birth. She was on it for three years before her mother found out. By that time, she had 15 accounts. “She’d have me put my phone in the living room at night. I’d wait ‘til she went to bed then I’d sneak it.”

Most fights she had with her mother were about the phone; taking it away would often result in tantrums. If Kaley couldn’t see who was liking her stuff, it sent her “into a panic.”

She “bought likes” to make herself look popular. She began using beauty filters immediately; at some point, nearly all of her posts had them.

In one video shown by her attorneys, she appeared as a quintessential pre-teen, slight and still developing. She told her online audience she had cried “tears of joy” at reaching 102 subscriptions, and asked them for likes and follows, something she’d learned from other content creators.

“I’m sorry for my ugly appearance. I don’t know why I look so fat in this shirt,” she said. “I look so ugly.”

Kaley’s feelings of low self-worth and negative comparison mounted. At 13, she was diagnosed with social phobia and body dysmorphia disorder.

Of particular relevance to the case—which focuses on how the apps are designed and function, rather than the third-party content they may host—Kaley described her experience with various design features of defendants’ platforms.

Notifications on both apps, she said, kept her going back to get “that rush,” even in the middle of the night. Once she was there, AutoPlay or “infinite scroll” would keep her entranced for hours. Her therapist at the time noted she broke down crying when a peer posted photos of her, because she couldn’t stand seeing pictures of herself without filters.

Competing Narratives

Attorneys are fighting to convince jurors of a competing narrative: In one version, she is an increasingly common casualty of rapacious companies that have “drugified“ every aspect of human connection for profit—in another, she is a troubled young woman whose difficult home life has left her with a litany of psychological damages that precede and overshadow her social media use.

Throughout the trial, plaintiff’s attorneys have used her age to anchor a chronology of what they say were defendants’ decisions to ignore clear, emerging evidence of wide-scale harms and engineer their products to be increasingly addictive as they raced to capture valuable youth demographics from competitors.

Lawyers for the plaintiff said that a cache of recently unsealed documents—internal presentations, reports, and communications chains totaling thousands of pages—proves the companies were aware of deleterious impacts their features had on young people’s well-being but targeted them anyway.

Instagram, the complaint alleges, targeted K.G.M. with its proprietary Artificial Intelligence tools, connecting her with “predatory adults,” serving her “harmful, depressive content, and leading in at least one instance to sextortion.

“These are connections and content K.G.M did not seek out or even want to see; instead they are the types of harms Defendants aimed at her in their efforts to prevent her from looking away at any cost,” according to the complaint.

Executives, including Meta CEO Mark Zuckerberg, Instagram head Adam Mosseri, and YouTube’s vice president of engineering Cristos Goodrow, have testified that their products are engineered not to be addictive, but to provide a valuable service to users.

Attorneys for YouTube, in their opening statement, suggested the app has been a net positive in Kaley’s life, serving as an outlet for her creativity and passion for video editing.

While some experts say instances of social media addiction are skyrocketing among young people and causing a litany of real-life harms, the phenomenon is new and there remains a lack of consensus about its meaning and implications; diagnosis and treatment are not standardized, and a sense of its true scope is unclear.

Defendants have argued K.G.M. suffered mental health impacts due to bullying and family difficulties, not social media use.

Hindsight

Phyllis Jones, an attorney for Meta, on Thursday attempted to impeach the testimony Kaley gave during a previous deposition about her home and family life.

Cross-examining the plaintiff, she suggested Kaley’s anxiety and depression may have stemmed from her relationship with an “absent” father and a “neglectful” single mother, both of whom were at times abusive.

Kaley said she may have said she felt that way at some point, but didn’t necessarily think it was true now.

Recounting difficult junctions in her relationship with her mother, Kaley suggested previous representations were “a dramatization.”

In fact, she said, she often posted dramatized versions of conflicts with her mother on social media to get attention.

Jones played jarring audio recordings taken by Kaley of her mother screaming at her, asking if she was scared at the time, or felt anxious.

“I posted this without the full context and this was not frequent,” Kaley said. “It’s her yelling about something I did, and most of the time it was about chores.”

Kaley said she is working on undoing the damage she claims was caused by an obsessive use of defendants’ platforms.

She still suffers from social anxiety and body dysmorphia, spending three to four hours getting ready in the morning. To get to court Thursday, she said she woke up at 3:50 a.m.

Still, she hopes to become a social media manager someday.

Asked if she uses beauty filters now, she told the jury, “I try to avoid using [them] because I know I’ll feel worse about myself. ... But I still do.”