New Delhi, Feb. 21 -- For years, social media companies have disputed allegations that they harm children's mental health through deliberate design choices that addict kids to their platforms and fail to protect them from sexual predators and dangerous content. Now, these tech giants are getting a chance to make their case in courtrooms around the country, including before a jury for the first time.

Some of the biggest players from Meta to TikTok are facing federal and state trials that seek to hold them responsible for harming children's mental health. The lawsuits have come from school districts, local, state and the federal government as well as thousands of families.

Two trials are now underway in Los Angeles and in New Mexico, with...