This paper offers a comprehensive overview of Japanese law and practice relating to iatrogenic (medically-caused) injury, with comparisons to other nations' medical law systems. The paper addresses criminal sanctions for Japanese physicians' negligent and illegal acts; civil law principles of substantive law and related issues of procedure, practice, and liability insurance; and administrative measures including health ministry programs aimed at expanding and improving the quality of peer review within Japanese medicine, and a recently implemented no-fault compensation system for birth-related injuries.

Among the paper's findings are these. Criminal and civil actions increased rapidly after highly publicized medical error events at the turn of the 21st century, peaked from 2004 (civil cases filed) to 2006 (cases police sent to prosecutors), and have since declined. Civil Code provisions of substantive law governing medical injury compensation differ little from rules applied in North America and Western Europe, although the burden of proof of causation is relaxed in informed consent and loss-of-chance cases. Damage awards appear to be at least as high on average as in the U.S., and are applied on a more consistent basis. Procedural reforms, including the institution of health care divisions of district courts in some metropolitan areas, have speeded up the pace of court proceedings.

The new no-fault compensation system for birth-related injuries, offering substantial profit opportunities (as well as a theoretical risk of loss) to private insurers, has achieved virtually universal buy-in by childbirth facilities hoping for protection from future litigation. Evaluation of the system's operation is still premature but worthy of scholarly attention. Should the obstetrical compensation system prove successful, it may serve as a springboard for the expansion of no-fault principles to cover a wider scope of medical injuries—a topic now under study.