Recent status of the medical examiner system in Japan: demographic variation of medicolegal deaths in Hyogo Prefecture and uncertainty in medicolegal investigations conducted by medical practitioners.

The medical examiner system has been steadily abolished in Japan. Instead, medicolegal investigations are entrusted by the police to medical practitioners, who are not permitted to perform autopsies. The necessity for the medical examiner system was assessed through inquest records in Hyogo, one of the three prefectures which still have medical examiner systems. Standardized mortality ratios (SMRs) for accidents and suicides were negatively associated with population density, being high in rural areas with a large proportion of elderly citizens, while the SMR for natural deaths was high in urbanized areas and associated with the proportion of inquests to total resident deaths. The high proportion of inquests, however, did not always mean that inquest records were of good quality. Significant differences in the quality of medicolegal investigations seemed to exist between medical examiners and medical practitioners. That is, in order to certify the cause-of-death, medical examiners performed autopsies in about half of their cases, while only 2% of medical practitioner cases were subjected to autopsies. Medical practitioners, who certified the cause-of-death as "heart failure" without advising an autopsy, were regularly entrusted with inquests. It is likely that the causes-of-death for medicolegal cases may be questionable since more than 85% of all medicolegal deaths were investigated by medical practitioners, which may cause inaccuracy in at least 3-7% of mortality statistics. It is necessary to educate medical practitioners concerning the importance of mortality statistics and ICD and on the validity of autopsies, in order to obtain accurate mortality statistics from medicolegal cases.