A landmark social media addiction trial in which top tech executives are expected to testify begins on Tuesday in California. The plaintiff, a 19-year-old woman identified by the initials KGM, alleges the design of the platforms' algorithms left her addicted to social media and negatively affected her mental health. The defendants include Meta - which owns Instagram and Facebook - TikTok's owner ByteDance, and YouTube parent Google. Snapchat settled with the plaintiff last week.

The closely watched case at Los Angeles Superior Court is the first in a wave of such lawsuits, which could challenge a legal theory used by tech firms to shield themselves from culpability in the US. The named social media companies have claimed the plaintiff's evidence falls short of proving they are responsible for harms such as depression and eating disorders.

The trial marks a distinct shift in how the US legal system treats tech firms amid mounting claims that their products lead to addictive behaviors. The companies argue that Section 230 of the Communications Decency Act exempts them from liability for third-party content.

However, this case focuses on the design choices regarding algorithms and notifications affecting user interaction. KGM's attorney, Matthew Bergman, highlighted this trial as a landmark moment where a jury will hold a social media company accountable.

Meta boss Mark Zuckerberg is among the expected testimonies, as the trial unfolds amidst increasing scrutiny from families and authorities regarding social media's impact on youth mental health. The outcome could signify a crucial turning point in how tech industry responsibilities are perceived and enacted in legal frameworks.}