Overview
- TikTok kept about 10 percent of U.S. users — roughly 15 million people — on an older recommendation system during an early 2022 A/B test so the company could compare engagement with and without the safety change.
- Sixteen‑year‑old Chase Nasca was in that control group and later died by suicide in February 2022, and TikTok’s reconstruction found his final two weeks included 7,563 videos with about 73 percent touching on mental‑health themes and nearly 10 percent violating rules on suicide and self‑harm.
- The internal report recommended shrinking control groups from 10 percent to under 1 percent and limiting tests to days instead of months while warning that even a 1 percent control would leave millions without the safeguard.
- The document is currently sealed by court order and its disclosure could be used in the Nasca family’s wrongful‑death appeal and in broader lawsuits testing whether platform design and testing choices create legal liability.
- TikTok says it has refined testing practices and remains committed to user safety but the case highlights how routine A/B experiments can create ethical and legal risks when they withhold protections from vulnerable users and regulators are likely to press for clearer rules.