A jury in LA has delivered a damning verdict for two of the world's most popular digital platforms, Instagram and YouTube.
It ruled those apps are addictive, and deliberately engineered that way – and that their owners have been negligent in their safeguarding of the children who have used them.
It's a sombre moment for Silicon Valley and the implications are global.
The tech giants in this case, Meta and Google, must now pay $6 million (£4.5 million) in damages to a young woman known as Kaley, the victim at the centre of this case.
She claimed the platforms left her with body dysmorphia, depression, and suicidal thoughts.
Both companies intend to appeal, with Meta maintaining a single app cannot be solely responsible for a teen mental health crisis.
Google, meanwhile, says YouTube is not a social network.
But for now, the ruling means the era of impunity is over according to Dr. Mary Franks, a law professor at George Washington University.
It could redefine the landscape of social media and even marks the beginning of the end of the social media era as we know it.
Kaley's court victory is now big tech's second defeat in numerous similar cases set for trial in the US this year. Legal experts predict more to come, signaling a shift in how courts view platform design as a set of choices that can carry real legal and social consequences.
The UK and other countries are considering laws around social media usage that aim to protect children from its potential harms, adding to the pressure on these platforms to adapt.
