SAN FRANCISCO — A U.S. appeals court has ruled that more than 3,000 lawsuits against major social media companies can move forward, creating a new legal challenge for some of the world's largest technology companies.

The cases involve Meta Platforms, Google's Alphabet, ByteDance's TikTok and Snap, with plaintiffs alleging that the companies deliberately designed their platforms to encourage addictive use, particularly among young people.

The 9th U.S. Circuit Court of Appeals rejected the companies' attempt to stop the litigation at this stage. The court said Section 230 of the Communications Decency Act provides a defense against liability rather than blanket immunity from lawsuits.

The ruling could have wider implications for the technology industry because the lawsuits focus not simply on user-generated content, but on how social media products and features are designed.

The companies continue to dispute the allegations and have argued that existing legal protections should shield them from the claims.

The legal pressure comes after separate cases produced significant verdicts and rulings involving alleged harm to young users. A multistate case involving 29 state attorneys general is also moving forward.

The latest ruling could become an important turning point in the debate over technology companies' responsibility for the design and effects of social media platforms.