Los Angeles, California - Jury deliberations are set to begin Friday in a landmark social media addiction trial accusing Meta and YouTube of intentionally trying to hook young internet users.

Closing arguments wrapped here Thursday with rival attorneys trying to convince jurors the evidence backed their side of the clash.

The verdict could turn on the question of whether family and other real world troubles, or YouTube and Meta apps such as Instagram, were to blame for mental woes of the woman who filed the suit.

An attorney for the woman, a 20-year-old California resident identified as Kaley G.M., used a cupcake metaphor, arguing that while only a small bit of baking soda might be in a recipe, it was essential for making the pastry.

"It comes down to highly technical legal standards," the plaintiff's attorney Laura Marquez-Garrett said of the job ahead for jurors.

"They could find all kinds of terrible stuff, but then determine that technically speaking, the percentage of contribution wasn't met."

An attorney for Meta, Paul Schmidt, noted that none of the therapists who testified had identified social media as the cause of Kaley's troubles.

Instead, he said, Kaley's records show emotional and physical abuse along with academic struggles and psychiatric conditions separate from her use of social media.

"Kaley has faced profound challenges, and we continue to recognize all she has endured," Schmidt said. "The jury's only task, however, is to decide if those struggles would have existed without Instagram."

YouTube, meanwhile, has likened itself to television during the trial, rebuffing the idea of equating it with online social media platforms.

Kaley testified at trial that YouTube and Instagram fueled her depression and suicidal thoughts as a child, telling jurors that she became hooked on social media, starting with YouTube videos, at the age of six.

Under cross examination, however, Kaley talked about feeling neglected, berated, and picked on by family members, causing depression and anxiety that apparently had nothing to do with social media.

She said her mother pushed her into therapy at around age 12, and that during the first session, she said she could not engage with her family at home because of "excessive worrying because of social media."

In a surprising twist, Kaley also said she would like to become a social media manager and capitalize on the skills she has built.

Meta's chief executive Mark Zuckerberg took the stand during the trial, pushing back against accusations that his company had done too little to keep underage users off his platform and had profited from their presence.

Zuckerberg told jurors that he regretted Meta's slow progress in identifying underage users on Instagram, but that "we're in the right place now."

YouTube vice president of engineering Cristos Goodrow said while testifying that the Google-owned company's aim was to give people value, not hook them on harmful binge-viewing, despite aggressive growth goals at the platform.

"We don't want anybody to be addicted to anything," he said.

The lawsuit is one of hundreds accusing social media firms of leading young users to become addicted to their content and suffer from depression, eating disorders, psychiatric hospitalization, and even suicide.

Internet titans have long shielded themselves with Section 230 of the US Communications Decency Act, which frees them of responsibility for what social media users post.

However, this case argues that the firms are responsible for defective products with business models designed to hold people's attention and to promote content that can harm their mental health.

The outcome of the Los Angeles trial is expected to establish a standard for resolving thousands of lawsuits that blame social media for fueling an epidemic of depression, anxiety, eating disorders, and suicide among young people.

If you or someone you know needs help, please contact the 24-hour National Suicide Prevention Hotline by calling or texting 988 for free and confidential support. You can also text "HOME" to 741741 anytime for the Crisis Text Line and access to live, trained crisis counselors.