In emergency cases, the police file a report with the prefectural governor on any offender who is suspected to be mentally disordered. In cases where the police do not perceive that emergency care is required, the person is sent to the public prosecutor’s office. Next, based on the results of a psychiatric evaluation, the public prosecutor makes a decision on the person’s criminal responsibility. If the person is deemed to be insane, the public prosecutor drops the case and files a report with the prefectural governor. However, if the person is deemed to have diminished responsibility, the charge can be dropped at the public prosecutor’s discretion. Based on a report by the public prosecutor, the prefectural governor orders two or more designated physicians to conduct an examination of the individual. When the designated physicians have agreed that the person is mentally disordered and liable to cause personal injury unless admitted to hospital, the prefectural governor orders the involuntary admission of that person, which must be concluded when the person is no longer regarded as a danger to others or to oneself.

This procedure applies to an individual who commits a serious criminal offense in a state of insanity or diminished responsibility. “Serious offenses” are specifically defined under the law as follows: homicide, robbery, bodily injury, arson, and sexual crimes (rape and indecent assault). All categories, except for bodily injury, include an attempt to act. There are two channels of referral by the public prosecutor to the District Court. The first channel concerns a person for whom the public prosecutor withdraws a charge. The second channel concerns a person who is acquitted or given a mitigated sentence without imprisonment in a criminal trial. Following a referral, the District Court orders a psychiatric evaluation and sets up a special panel which consists of a judge and a psychiatrist. Based on the results obtained from the psychiatric evaluation, the two panel members exchange opinions based on their respective legal and medical backgrounds and agree upon a verdict. Possible verdicts include an inpatient treatment order, an outpatient treatment order, or no treatment order. The Act stipulates that the Court shall order treatment “if it is deemed necessary to provide the person with treatment under the law in order to improve the person’s mental conditions that existed at the time of the act and to promote his or her rehabilitation without recurrence of a similar act”. Multidisciplinary personnel in a “designated inpatient treatment facility” carry out the inpatient treatment. A person who is given an outpatient order or whose inpatient order is concluded is placed under “mental health supervision”, according to which mental health facilities and probation services collaborate to help patients live in the community.

Following the prosecution of a person who is judged to have full or diminished responsibility, the Court may order an additional psychiatric evaluation. If the person is acquitted or given a mitigated sentence without imprisonment, he or she shall be placed under the Mental Health and Welfare Act (in case of minor offenses) or the Medical Treatment and Supervision Act (in case of serious offenses). Imprisoned offenders may be given psychiatric treatment in correctional institutions as discussed in the next part of this chapter.

To summarize, the Japanese legislation is unique in that offenders with mental disorders are treated within three distinct systems, namely, general psychiatry under the Mental Health and Welfare Act, specialist forensic psychiatry under the Medical Treatment and Supervision Act and prison psychiatry under the Inmates and Detainees Act. However, the links among these systems are very limited. The enforcement of the Medical Treatment and Supervision Act has certainly established a new era in the management of offenders. However, as discussed later, mentally ill inmates in correctional institutions are unlikely to benefit from this progress.

Based on official statistics, 2,859 offenders were mentally disordered or suspected of having a mental disorder in 2008, accounting for approximately 0.8 % of the total number of individuals arrested for penal code offenses (Research and Training Institute 1990–2009). However, since these figures are contingent upon police involvement, it is probable that the rate of mental disorders within the offending population was underestimated, particularly for those suffering from milder disorders, including mild mental retardation or certain types of personality disorders. Since the rate was reported to be 0.6 % in 1999, there has only been a slight increase over the past 10 years. The percentage rates were relatively high among individuals who committed arson (14.3 %) and homicide (10.2 %). Among those 2,859 mentally disordered offenders, 520 were not indicted by the public prosecutors and 11 were acquitted by the courts for reasons of insanity (Research and Training Institute 1990–2009).

In that same year, the public prosecutors referred 379 individuals who committed serious offenses to the District Court in accordance with the Medical Treatment and Supervision Act. The majority (88 %) of them were referred to the Court after their charges were dropped. Based on the court’s decision, 257 cases were given an inpatient treatment order, while 62 were given outpatient treatment orders (Research and Training Institute 1990–2009). After the implementation of the Medical Treatment and Supervision Act in 2005, there have been no substantial changes to these figures and estimates.

According to the Mental Health and Welfare Act, persons who commit offenses that are not regarded as serious may be involuntarily admitted to a hospital based on an order from the prefectural governor. In 2008, the number of this form of admission was 2,066, accounting for 0.6 % of all admissions to psychiatric hospitals (Research Group on Mental Health and Welfare 2010). The number of these involuntary admissions has gradually decreased since the time of the Mental Hygiene Act, the predecessor of the Mental Health and Welfare Act. Since the provision for this category of admission applies not only to persons who are deemed dangerous to others, but also to those who are at risk to injure themselves, it is impossible to infer how many offenders may be included in this category.

Thus, according to the aforementioned figures and estimates there have been little increases in the number of offenders who have been treated within the provisions set forth by either general or specialist forensic psychiatry in recent years.

In contrast, the number of incarcerated inmates diagnosed with mental disorders is increasing in correctional institutions. Moreover, the number of inmates who were diagnosed as having any kind of mental disorder aside from personality disorders on admission has been gradually increasing. While the estimate of inmates was 876 (3.6 % of the total of newly admitted inmates) in 1999, it grew to 1,835 (6.3 % of the total of newly admitted inmates) in 2008. Among those recognized as mentally disordered in 2008, 237 had mental retardation; 253 had neurotic disorders, while 1,214 had other mental disorders, such as schizophrenia, substance use disorders, or mood disorders (Research and Training Institute 1990–2009).

Figure 13.2 illustrates the changes over the past decade based on results from a 1-day annual survey (Mochizuki et al. 2010).

The data represent two specific groups. The first group is comprised of inmates who had to leave work due to illness; while the second group was comprised of inmates who remained at work while receiving medical treatment. Presumably, the inmates from the first group suffered from more serious illnesses. In 2008, the number of inmates in the first group was 259 (0.3 % of the total number of inmates), while the number of inmates in the second group was 5,486 (7.1 % of the total number of inmates). Thus, the numbers had increased for both groups. In particular, the number of people in the second group had doubled over the past 10 years. As for the distribution of mental disorders according to ICD-10 (World Health Organization 1992), among the first group the diagnostic category of F2 (schizophrenia, schizotypal and delusional disorders) was most prominent, accounting for 39 % of the total. Among the second group, F1 (mental and behavioral disorders due to psychoactive substance use) was the most common diagnostic group accounting for 37 % of the total, followed by F3 (mood disorders) and F4 (neurotic, stress-related and somatoform disorders).

Although details of clinical profiles are not available, some conclusions can be drawn from the aforementioned prevalence figures. Symptoms of schizophrenia tend to be chronic and debilitating. Consequently, it appears that correctional institutions accommodate a considerable number of inmates who are unable to serve their term of “imprisonment with work” due to schizophrenia.

Additionally, the high prevalence of psychoactive substance use disorders is another important issue. It has been suggested that a large number of those inmates diagnosed with F1 disorders are addicted to methamphetamines, which is the most commonly abused drug in Japan (Research and Training Institute 1990–2009). Due to the fact that methamphetamine-induced mental disorders are often prolonged, even up to several years after cessation of substance use, some inmates with addictions may require continuous psychiatric treatment.

With regard to an increase in the number of patients with mood or neurotic disorders, the aging rate of the prison population may be relevant here; however, this cannot be confirmed due to the lack of available data.

It is interesting to compare the aforementioned figures with data and figures from international studies. For example, Fazel and Danesh (2002) examined serious mental disorders in 23,000 prisoners by reviewing 62 surveys from 12 Western countries and found that among male prisoners, 3.7 % had psychotic illnesses, and 10 % had major depression. Interestingly, among female prisoners, 4.0 % had psychotic illnesses, while 12 % had major depression. In contrast, in Japan, 1.1 % of prisoners (both male and female) were diagnosed with schizophrenia, schizotypal or delusional disorders, and 1.5 % were diagnosed with mood disorders. Therefore, the percentages of inmates with serious mental disorders in Japan appear to be substantially lower compared to Western countries. This discrepancy may be due in part to the differences observed in screening procedures for mental illnesses. In Japan, it is likely that some mentally ill inmates are overlooked due to the shortage of psychiatrists and other mental health care professionals (Kuroda 2008). However, various additional factors may contribute to this discrepancy, and further studies are needed to investigate these differences.