Legal Principles and Causal Inference Issues in Tobacco Litigation: Lessons from Korea

This study examines the legal principles and causal inference challenges in tobacco litigation, with a focus on the South Korean context. Drawing on qualitative legal analysis and an epidemiological framework, it reviews landmark judicial decisions involving both individual plaintiffs and the National Health Insurance Service (NHIS) in lawsuits against major tobacco companies. The methodology includes a comprehensive doctrinal analysis of court rulings, evidentiary standards, and legal reasoning related to causality, alongside a comparative review of international case law. The study also incorporates epidemiological criteria and metrics such as relative risk, attributable fraction, and probability of causation to evaluate how scientific evidence has been presented and interpreted in legal proceedings. By interrogating the intersection of law and public health science, the paper highlights how the legal distinction between specific and non-specific diseases complicates the judicial recognition of causality in tobacco-related cases. It further draws parallels with environmental litigation to argue for a reduced burden of proof in tobacco lawsuits, advocating for greater evidentiary weight to be given to epidemiological findings. Through cross-national comparisons, the study calls for legal reforms that more closely reflect public health imperatives, ultimately promoting fairness, accountability, and stronger tobacco control.