Edith HejbergZuckerberg testified just feet away from Kaley, who sat in the courtroom to hear him speak.
Meta CEO Mark Zuckerberg took the stand in Los Angeles on Wednesday, facing sharp questions about whether Instagram was designed to be addictive for children.
It marked the first time he testified before a jury in a case centered on claims that social media harmed young users’ mental health.
At the heart of the trial is a now-20-year-old woman, identified as “Kaley,” who says Meta and YouTube hooked her as a child and caused lasting damage.
Facing the accuser in court
Zuckerberg testified just feet away from Kaley, who sat in the courtroom to hear him speak.
Her attorney, Mark Lanier, has said she struggles with social anxiety and would not attend most of the proceedings.
Still, her presence underscored the personal stakes of a case that could ripple across the tech industry.
Parents gather outside the courthouse
Before proceedings began, nearly a dozen parents gathered outside Los Angeles Superior Court.
Some say their children were harmed, or even died, because of social media.
They described a company that, in their view, “preyed on teens” in pursuit of profit.
“I navigated this in a reasonable way”
On the stand, Zuckerberg defended his leadership.
He said he believed he had handled young users’ safety “in a reasonable way.”
“We get feedback from a handful of different stakeholders, including people who study wellbeing,” he testified. “I took into account all of that info and I think I navigated this in a reasonable way.”
A mother’s grief and accusation
During a break, Julianna Arnold spoke to reporters about her 17-year-old daughter, Coco, whose death she traces to Instagram.
“It was surreal” to see Zuckerberg testify, she said, after years of pushing for change.
“The intention of the company was to prey on teens … exploit them so they can make greater profits,” Arnold said. “That was done intentionally, not by accident.”
The dramatic display of instagram posts
As questioning wrapped up, Lanier introduced a striking visual: a long poster covered with hundreds of photos Kaley had posted to Instagram.
Seven people held it up in court.
The display aimed to highlight what her legal team calls compulsive use of the platform.
Under-13 users and age checks questioned
A key issue was whether Instagram allowed children under 13 to join.
Zuckerberg said younger children are “not allowed on Instagram.”
But Lanier presented a 2015 internal document estimating more than 4 million users under 13, “30% of all 10-12 year olds in the US.”
A late shift to birthdate verification
Lanier noted that Instagram did not require new users to enter their birthdate until December 2019.
Before that, users simply confirmed they were over 13.
Kaley, who says she joined at age 9, was never asked to provide her age when she signed up.
Claims of addiction and mental harm
Kaley’s lawsuit alleges she spent “several hours a day” on Instagram and once logged more than 16 hours in a single day.
She says the platform’s features contributed to anxiety, body dysmorphia and suicidal thoughts.
She also claims she experienced bullying and sextortion through the app.
Meta pushes back
Meta has said “we strongly disagree” with the allegations and is “confident the evidence will show our longstanding commitment to supporting young people.”
The company argues that Kaley’s mental health struggles stemmed from challenges in her family life, not social media.
YouTube also denies the claims.
Time spent vs. “utility and value”
Lanier pressed Zuckerberg on whether Meta once set goals to increase time spent on Instagram.
An internal 2015 email referenced a plan including “Time – +10% for Instagram.”
Zuckerberg said such goals existed “earlier on in the company” but were later replaced with a focus on “utility and value.”
Filters, free expression and expert advice
The trial also examined Instagram’s decision to allow user-created “beauty” filters.
Lanier said Meta consulted 18 experts who found such filters can cause harm.
Zuckerberg testified that the company chose to allow users to create them but not promote them, saying he believed “the balance of free expression” justified that approach.
Billions at stake, and what comes next
Legal experts say the jury will weigh whether Instagram was a substantial factor in Kaley’s struggles.
If Meta and YouTube lose, they could face billions in damages and pressure to change their platforms.
As one attorney put it, the case may come down to a simple question: are they doing enough, and do they care?
