After rejection of the originally submitted Race Eugenic Protection Law in 1938, National Eugenic Law (Kokumin Yūsei Hō) was promulgated in 1940 by the Konoe government.[1] This law limited compulsory sterilization to "inherited mental disease", promoted genetic screening and restricted birth control access.[1] According to Matsubara Yoko, from 1940 to 1945, 454 people were sterilized in Japan under this law.[1]

The National Eugenics Law (Kokumin Yūsei Hō) existed from 1940 to 1948 and aimed, "from the standpoint of eugenic policy, to increase those with healthy qualities and reduce genetic diseases." It therefore regulated **sterilization (eugenic surgery) for persons with genetic diseases** and restricted induced abortion for those with "sound qualities." Under Article 5(1), when an eligible person had not yet reached 30 years of age, an application for eugenic surgery required the consent of the parents in the household, obtained by the director of a mental hospital or a public health center or by a doctor designated by ordinance, who would apply for the surgery **with the patient’s consent**. The article also provided for a regime of "compulsory sterilization" in Article 6, though Wikipedia notes that **no operations were carried out under this compulsory provision**.

The National Diet Library legislative survey describes the National Eugenics Law as creating two categories of eugenic surgery: **voluntary (Article 3) and compulsory (Articles 4–11)**. Voluntary surgery required consent capacity and the consent of the individual (and spouse, if any). In contrast, **compulsory eugenic surgery** could be initiated "when the physician, as a result of diagnosis, confirms that the person suffers from a disease listed in the table attached to the law and considers that, to prevent the heredity of the disease, it is necessary in the public interest to perform eugenic surgery." In that case, "the physician may apply to the prefectural Eugenic Protection Committee for examination of the propriety of performing eugenic surgery **without obtaining the consent of the person and the spouse**," and if the committee decides the surgery is appropriate, a designated physician performs it.

Mizubayashi’s study of Japan’s eugenics legislation explains that Chapter 2 (Articles 3–11) of the National Eugenics Law regulated eugenic surgery and established **two types**: first, "eugenic surgery based on consent" (Article 3), where the consent of the person and, when there was a spouse, the spouse, was a condition for surgery. Second, Article 4 provided for **compulsory eugenic surgery**. It states that when a physician diagnoses a person as having one of the diseases listed in the attached table and recognizes that performing eugenic surgery is necessary in the public interest to prevent heredity of the disease, **the physician may apply to the prefectural Eugenic Protection Committee for examination of the propriety of performing eugenic surgery without obtaining the consent required in the previous article**. Procedures were set out in Article 5, where the committee examined whether the surgery was necessary for the protection of the person and decided on its propriety, then notified the applicant and the consent-giver referred to in the previous article.

In response to these opinions, the government enacted the "National Eugenic Act" (1940). The National Eugenic Act is, in brief, the Sterilization Act. Social Darwinism was behind the enactment of this law. A radical logic claims that the birth of humans with recessive factors should be fundamentally blocked prior to the stage of fertilization to prevent elements harmful to society.[2]

Hashimoto’s empirical study on eugenic surgery under the National Eugenics Law (1940–1948) focuses on three sterilization cases examined by the Tottori Prefecture Eugenics Review Committee. The paper reconstructs "the process that led to eugenic surgery for these three people, the discussions at the Eugenics Review Committee, and the situation after surgery." It shows that **prefectural-level committees composed of medical and administrative experts deliberated on applications and decided whether surgery should be performed**, indicating that decisions were not solely left to the individuals concerned but involved formal review by expert bodies.

The House of Representatives research report on the enactment of the National Eugenics Law notes that leading psychiatrist Yoshimasu Osao, who was deeply involved in advocating a sterilization law through the Japan Ethnic Hygiene Association, argued that given the small number of psychiatrists in Japan, the law should be based primarily on **voluntary sterilization**, with **compulsory measures only in special cases**. The report describes the legislative process by which the government, facing opposition in the Imperial Diet, promised **not to implement Article 6 on compulsory sterilization for the time being**, even though the legal framework for applications by mental hospital directors and other third parties without the individual's consent remained in the statute.

Sterilizations focused on criminals and people with perceived genetic disorders such as colour-blindness, hemophilia, ichthyosis, and mental illnesses such as schizophrenia. Japan’s first law to allow forced sterilization was passed in 1940, the National Eugenic Law. The law allowed for the sterilization of people deemed genetically inferior, and decisions were made by authorities under the law rather than by the individuals themselves.[9]

The Ministry of Health and Welfare pamphlet "Eugenic Protection Law in Japan" (latest revised edition) is an official document outlining the post‑1948 law’s mechanisms, which evolved from the National Eugenic Act. It details that applications for eugenic surgery were submitted to and decided by Prefectural Eugenic Protection Commissions, consisting of physicians and appointed officials, and that operations could proceed without the patient's consent if the commission approved.[10] Although focused on the 1948 law rather than the 1940 Act, it shows that in Japan’s eugenic legislation, formal decision‑making power over sterilization rested with medical experts and administrative bodies rather than solely with individuals seeking surgery.[10]

An analysis from the Japan Association for Local Government Research explains that under the postwar Eugenic Protection Law (the successor to the National Eugenics Law), eugenic surgery (sterilization) could be performed for "eugenic reasons" either with the consent of the person and spouse (Article 3) or **without the person’s consent** when certain conditions such as mental illness were met, following review by a prefectural Eugenic Protection Review Committee (Articles 4 and 12). These committee-based procedures for **non-consensual sterilization** were rooted in the earlier framework created by the National Eugenics Law of 1940, which had already distinguished between consent-based and compulsory surgeries and placed decision-making power in medical experts and government-appointed committees.

Under the Eugenic Protection Law (EPL), in place from 1948 to 1996, people with intellectual or mental disabilities, and those with certain hereditary diseases, were sterilised "to prevent birth of inferior descendants from the eugenic point of view, and to protect life and health of mother, as well". Of the roughly 25,000 people sterilised under EPL, about 16,500 were made to against their will, and some without their knowledge. A 1,400-page report submitted to parliament found up to 8,000 patients who gave their consent were pressured into doing so. Local governments at the time had the power to arbitrarily assign the surgery.[4]

CNN’s account of the Supreme Court ruling explains how sterilizations were carried out under Japan’s eugenic legislation: "The Eugenic Protection Law, which was active from 1948 until 1996, permitted authorities to carry out sterilizations on individuals with disabilities, including those suffering from mental health issues, hereditary ailments, physical deformities, and leprosy."[3] It states that "approximately 25,000 individuals were sterilized without their consent during this timeframe, based on data from the ministry" and that the law aimed "to prevent the rise of inferior descendants from a eugenic perspective."[3] The description emphasizes that legal authority and medical practitioners, rather than the individuals, decided and implemented sterilization procedures, reflecting institutional practices that developed from the earlier National Eugenic Act.[3]

Japan's Supreme Court has ordered the government to compensate people who were forcibly sterilised under a 'eugenic protection law' that was only repealed in 1996. About 16 500 people were forcibly sterilised, some as young as 9, under the law which was passed in 1948 "to prevent the birth of defective offspring from a eugenic point of view," according to its opening clause. Roughly 8500 more were sterilised after they or their parents gave consent that was obtained under intense pressure from the state.[5]

The law, in place for 48 years, forced people to undergo operations to prevent them having children deemed "inferior". On Monday, parliament released a long-awaited 1,400-page study. It acknowledged that about 25,000 people had been subjected to operations – more than 16,000 of which were performed without consent. Local governments at the time had the power to arbitrarily assign the surgery. Some people were told that they were undergoing routine procedures like appendix operations.[7]

The "Eugenic Protection Law" allowed the forced sterilization of people with disabilities and other health conditions with the purpose of preventing the birth of disabled children. From 1948 to 1996, almost half a century, the law remained in effect. Amidst the turmoil of the Second World War, the first law to allow forced sterilization was passed. Because of the circumstances of the time, the Eugenic Protection Law was adopted after the war and sterilizations began. In addition to those with disabilities deemed "hereditary," people with non-hereditary mental and intellectual disabilities became subject to sterilization. Under the Eugenic Protection Law, deaf people too were subject to the surgery.[6]

The article "What was the National Eugenics Law in prewar Japan?" explains that the National Eugenics Law, enacted in wartime 1940, was a law concerning sterilization and abortion. It notes that during Diet deliberations, there was strong opposition to Article 6 on **compulsory sterilization (dansa)**, which allowed "third-party applications such as by mental hospital directors" for sterilization "without requiring the consent of the person." In response, the government pledged that while the clause would remain, **compulsory sterilization would not be implemented for the time being**, and in practice no operations were carried out under Article 6. At the same time, the law made it obligatory to submit prior notification and seek another doctor’s opinion for all non-eugenic sterilization surgeries, indicating broader **medical and administrative control over reproductive surgery decisions**.

The Supreme Court of Japan struck down the Eugenics Protection Law (1948–1996) as unconstitutional and ordered the government to pay compensation on 3 July 2024. The Court recognised that many of the sterilizations were conducted without the free and informed consent of the individuals concerned, under procedures that empowered doctors and administrative bodies to decide on operations. The ruling examined how Prefectural Eugenic Protection Councils and medical experts authorised surgeries under the law.[10]

A demographic-policy study on the National Eugenics Law points out that before the law, sterilization surgeries were not regulated by statute, while abortion was only constrained by the Penal Code’s crime of abortion. The National Eugenics Law introduced regulations that combined **policies concerning the "quality" of the population (eugenic control of hereditary diseases) and "quantity" policies (control of abortion)**. It emphasizes that for sterilization, the law established **legal conditions, procedural requirements, and involvement of medical professionals and authorities**, replacing purely private decisions with a system in which doctors and administrative bodies played central roles in authorizing operations.

A paper on ethics in Japanese eugenics policy outlines the sequence "National Eugenics Law (1940), Eugenic Protection Law (1948), Maternal Protection Law," and notes that one reason the National Eugenics Law **restrained sterilization (断種) operations** was Japan’s particular ideology of the national polity (kokutai). It remarks that, despite the formal distinction between voluntary and compulsory sterilization, in practice, eugenic decisions were heavily influenced by **state ideology, medical experts’ views, and institutional policies**, rather than solely by autonomous choices of the individuals targeted by the law.

A legal commentary on the unconstitutionality judgments concerning the old Eugenic Protection Law notes that the National Eugenics Law of 1940 was its predecessor, and that the system of eugenic surgery and review by committees carried over into the postwar legislation until eugenic surgery was abolished in 1996 when the law was renamed the Maternal Protection Law. It underscores that **medical professionals and government-established committees had long held the authority to decide on eugenic sterilization**, forming a structural background for later court findings that such systems violated the rights of those who had been sterilized without genuine consent.

Japan’s first law to allow forced sterilization was the National Eugenic Law of 1940, which targeted criminals and those with perceived genetic disorders. Subsequent legislation, particularly the Eugenic Protection Law of 1948, institutionalised systems in which doctors, local governments, and Eugenic Protection Councils evaluated and approved sterilization procedures. Individuals subjected to these operations often had little or no say in the decision-making process.[9]

We find the term in the national eugenics law of 1940, which was replaced in 1948 by a eugenic protection law; in 1996 it was withdrawn from ...