Social media giants Meta and YouTube have been found liable by a California jury for negligence that caused harm to a young woman’s mental health. The landmark decision is among the first of many similar cases, and could be the beginning of a trend that may force major changes in how social platforms work.

The companies have been ordered to pay $3 million in compensatory damages, which are meant to cover the plaintiff’s financial losses related to the events relevant to the case, as well as pain and suffering. The jury has not yet decided the amount of any punitive damages – money the companies would pay as punishment for their actions.

The claim held by the young woman at the centre of the trial, known in court documents as KGM, was that the addictive nature of these social media products led to her anxiety and depression, and the jury agreed. Originally, the lawsuit included Tiktok (owned by ByteDance) and Snapchat (owned by Snap) as well, but they settled out of court before the trial began.

This case was not unique: thousands of similar lawsuits have been filed against social media companies across the US alleging that their products are addictive and harmful. Most of the cases have not yet gone to trial, but one in New Mexico was decided on 24 March, with a similar outcome. In that case, the state alleged that Meta failed to protect children from exploitation on its platforms, and a jury found the company guilty. Meta was ordered to pay $375 million in damages.

The question now is whether cases like this will result in substantive changes to the social media products that have been ruled to be harmful. In the US, free speech laws have made it difficult to demand any changes to social media platforms – in particular, one called Section 230 that prevents companies from being held liable for content posted on their platforms by users. But those same laws have made it difficult to win lawsuits like these, so this may well be a turning point.

The New Mexico case is moving towards a second phase, in which a judge will decide what changes, if any, Meta will be required to make to its social media platforms going forward.

A Meta spokeperson told New Scientist that the company disagrees with the verdicts and intends to appeal in both cases. Jose Castañeda, a spokesperson for Google, which owns YouTube, stated that the company intends to appeal the California decision. Several more lawsuits are set to go to trial in the coming months, and if this trend continues, it could force sweeping changes to the social media landscape.