The young woman at the heart of what has been called the tech industry’s “big tobacco” moment was on YouTube at six and Instagram by nine. More than a decade later, she says, she still can’t live without the social media she became addicted to.

“I can’t, it’s too hard to be without it,” Kaley, now 20, told a jury at Los Angeles’ superior court. This week, five men and seven women handed down a verdict on the design of two of the world’s most popular apps that vindicated Kaley’s position.

The ruling sent shockwaves through Silicon Valley and sparked hope among families and child safety campaigners that change may finally be coming to social media. Mark Zuckerberg’s Meta and Google’s YouTube were found liable for deliberately designing addictive products used by Kaley and millions of other young people.

It was one case centred on the suffering of one young person who became depressed at 10 and self-harmed, but Kaley, referred to by her first name or the initials KGM in order to protect her privacy, was the figurehead for a much bigger fight.

“We wanted them to feel it,” one of the jurors explained to reporters. “We wanted them to realise this was unacceptable.”