The world's largest social media companies have been accused of creating addiction machines as a landmark trial began in California examining the mental health effects of Instagram and YouTube.

In his opening argument before Los Angeles Superior Court Judge Carolyn B. Kuhl and a jury, Mark Lanier argued that his client, plaintiff K.G.M., suffered from mental health issues as a result of her social media addiction.

These companies built machines designed to addict the brains of children, and they did it on purpose, Lanier said.

Lawyers for Meta and YouTube told the jury that K.G.M.'s addiction stemmed from other issues in her life, not their negligence. K.G.M. will be referred to by her initials because the alleged harms took place when she was a minor.

Lanier charged that Meta and YouTube failed to warn of the dangers to young users posed by the design of their platforms, underscoring his remarks with a display of blocks spelling Addicting, Brains, and Children. He stated, This case is about two of the richest corporations in history who have engineered addiction in children's brains.

Lanier claims to have evidence from internal documents and emails that showcase the addictive design strategies of these platforms. An email from 2015 attributed to Zuckerberg discussed a demand for increasing user time spent by 12%.

The trial will include testimonies from experts, family members, and possibly from top executives at Meta and YouTube, with significant implications for ongoing lawsuits across the country.

Jurors will hear from former Meta employees who have raised concerns about social media addiction, as well as testimonies from families affected by these issues. The outcome may set a precedent for how children's online safety is managed and how legal accountability applies to social media companies.