(The paper presented at UNESCO-Kumamoto University Bioethics Roundtable 2007, "Perspectives on Self-Determination," December 16, 2007)

Self Determination by Imperial Japanese Doctors: Did They Freely Decide to Perform Deadly Experiments?

Associate Professor, Department of Philosophy
Faculty of Literature and Human Sciences
Osaka City University

Between 1933 and the end of World War II, Japanese doctors, mostly under the aegis of the Japanese Imperial Army, killed thousands of humans in the name of medicine. These medical atrocities includes training of army surgeons, biological warfare maneuvers, and research with humans. The human researches, which included vivisection, fell broadly into three categories: explaining diseases, development of therapies, and biological and chemical warfare research and development. Most of the human experimentation took place in Japanese-occupied Manchuria and China, although the Japanese army also operated experimental centers in Southeast Asia and on the main Japanese islands. Most of the victims were Manchurian or Chinese criminals, political prisoners, or prisoners of war, although some Allied prisoners of war such as Americans, Australians, and New Zealanders were also used and killed in these experiments. (for more details, see Tsuchiya 1997; Tsuchiya forthcoming)

In terms of "self determination" one of the most vexing questions is "did these doctors decide to participate in such atrocities voluntarily?" Their evident inhumanities may seem to refuse any explanation, some may say that they must simply be condemned. But without scrutiny of their situation of participation, we cannot judge their deed exactly. That's why I inquire into this question.


Voluntariness is an essential element for free and informed consent, along with disclosure, comprehension, competence, and consent. (U.S. National Commission 1978, U.S. President's Commission 1982; Meisel and Roth 1981) Beauchamp and Childress regard it as one of two "threshold elements (preconditions)" of informed consent along with competence. (Beauchamp & Childress 1994) Not only for informed consent, voluntariness is essential for free choice in general. But how can it be accomplished in concrete situations?

In fact, Nuremberg Code declared conditions in which person can "exercise free power of choice" as "without the intervention of any element of force, fraud, deceit, duress, over-reaching, or other ulterior form of constraint or coercion." But how can these all conditions be fulfilled? Do we usually decide under such an ideal situation?

Faden & Beauchamp would not use the term 'voluntariness' because of its ambiguity. Instead they use 'non-control' to one of three elements of autonomous action along with intentionality and understanding. They formulated that fully non-controlled act as having "either (1) not been target of an influence attempt, or (2) if they have been the target of an attempt to influence, it was either not successful or it did not deprive the actor in any way of willing what he or she wishes to do or believe." (Faden & Beauchamp 1986: 258) By contrast, the completely controlled acts "are entirely dominated by the will of another; they subject the actor to serve as the means to the other's ends and in no respect to serve the actor's own ends." (ibid.) Most concrete actions are placed in between these two poles of fully non-controlled and completely controlled.

Faden & Beauchamp also analyzes influence into three forms, namely coercion, manipulation, and persuasion. Manipulation is continuum concept, works both controlling and noncontrolling, and admits of degrees. On the other hand, coercion and persuasion are no continuum ones. "Coercion is always controlling, but not by degrees; persuasion is never controlling and involves no degree of noncontrol." (ibid.: 258)

So, if a person is regarded as really persuaded to do something, not coerced nor manipulated, his decision is always noncontrolling, namely voluntary. By contrast, if she is coerced, her determination is throughly controlled, namely involuntary. And if he has been manipulated, his decision can be partly controlled and partly noncontrolled, according to the content of manipulation.

Hereafter I investigate two cases of Imperial Japanese doctors if and how much their determination to participate in medical atrocities was voluntary or coerced. Taking these hard cases, we will reflect the way to find out elements of voluntariness in decision making.

The first case is that of Prof. YOSHIMURA Hisato, who is infamous of performing gruesome freezing experiments in Unit 731. At the end of the war he succeeded in escaping from Manchuria, got war crime immunity, returned to university, and finally became the president of Kyoto Prefectural University of Medicine.

The other case is of Dr. YUASA Ken, who participated in murderous surgical trainings killing 14 Chinese. After the war Yuasa and his division entered the army of Chinese Nationalist Party fighting against Communist until April 1949 when they finally surrendered. Yuasa was arrested and investigated by Chinese prosecutor. He fully recognized his crime, and since he returned to Japan in 1956 he has been repeatedly confessing his commitment.

These two cases stand in sharp contrast. Yoshimura throughly denied his performance of deadly experiments though his own published papers suggested that. On the other hand, Yuasa has been publicly confessing his crimes against humanity.


YOSHIMURA Hisato had been a lecturer at Kyoto Imperial University Faculty of Medicine before he joined Unit 731 in 1938. He stayed there until Unit 731 collapsed in 1945, and he used captives in studies of frostbite. He was employed as an Army Engineer, a researcher who was treated like officer but not a professional military serviceperson. Unit 731 was constituted by many laboratories, which were run by Army Engineers like Yoshimura. Many officers and soldiers of Unit 731 testified about the cruelty of Yoshimura's experiments.

For example, KURAKAZU Satoru, a Sergeant Major of Military Police at Unit 731, testified at Khabarovsk Trial in 1949:

When I walked into the prison laboratory, five Chinese experimentees were sitting on a long form [bench]; two of these Chinese had no fingers at all, their hands were black; in those of three others the bones were visible. They had fingers, but they were only bones. Yoshimura told me that this was the result of freezing experiments. (Materials 1950: 367)

Yoshimura himself gave a lecture on his frostbite studies in Harbin in 1941, describing an experiment freezing subject's middle finger. (Yoshimura 1941) After the war, he and his colleagues published three papers in Japanese medical journals in English reporting part of their studies, including not freezing but chilling finger experiments to nearly 0 degree of Celsius with ice-water. (Yoshimura & IIda 1950-51, Yoshimura & IIda 1951-52, Yoshimura, IIda & Koishi 1951-52) They wrote, "The experiments were made on about 100 male subjects (laboratory workers, students, soldiers and laborers)." (Yoshimura & IIda 1950-51: 149) Women, children, and even a 3rd day old baby were included in the experiments. (Yoshimura & IIda 1951-52: 177-179)

Yoshimura wrote his autobiography in 1984 and explained his situation of participation in Unit 731. (Yoshimura 1984: 29-34, 304-306, 311, 313-320) Not only he fiercely denied performing cruel experiments, his book was full of excuse, since he was severely blamed by the public when popular writer MORIMURA Seiichi describes Yoshimura's experiments in his million-seller Akuma no Hoshoku (Morimura 1981). As we know there were many evidences like above described, we cannot believe all his story. But at least we can know how he was situated to participate in Unit 731.

Yoshimura was ordered to go to Unit 731 by his head professor SHOJI Michinosuke, then was the professor of Physiology of Kyoto Imperial University Faculty of Medicine. Shoji sympathized militarism of ISHI Shiro, who was the founder and commander of Unit 731, and preached Yoshimura that medicine must contribute to the army. Yoshimura wrote he immediately refused his professor's order, because he was so interested in physiological studies. He was specialized in physical chemistry. Shoji told again Yoshimura that it's a good opportunity to know the social role of physiology in wartime and find how to devote onself to the country. Yoshimura was still reluctant, and let his mother visit Shoji to ask excuse, but in vain. Shoji said to Yoshimura's mother that he would ask the commander to return Yoshimura to Japan in 2 or 3 years. Yoshimura himself asked Shoji to postpone participation for 6 months in order to finish his work, but Shoji did not permitted at first. In return Shoji declared to Yoshimura that he would excommunicate Yoshimura from his department if not followed his order. It would result in the destruction of Yoshimura's academic careers. But still Yoshimura refused and answered in tears that he would give up physiological research. Finally Shoji allowed to give 6 months, and in this grace period Yoshimura finished writing his book A Theory and Measurement of pH (Yoshimura 1940).

Yoshimura explains how strongly his head professor Shoji ordered him and how hard he tried to resist it. Yoshimura apparently knew that Unit 731 was established for biological warfare. He wrote, "since Ishii Unit was an epidemic-prevention [=germ warfare] unit, I thought there was no place for physiologist." (Yoshimura 1984: 313)

Shoji apparently had promised Ishii to send his best disciple as soon as possible, but can nevertheless negotiate about the moment.

Yoshimura wrote that his colleague SAITO Koichiro, who participated in Unit 731 with Yoshimura, asked Shoji to let him return to Japan. Shoji agreed, and Saito spent only 1 or 2 years at Unit 731. Thus, researchers of Unit 731 could quit when his head professor called him back.

But Yoshimura explained he could not because Shoji and Ishii did not allowed. He stressed how much he hated to live in Unit 731 and how badly he wanted to return to Kyoto. "Professor Shoji sent us, his disciples, to Ishii Unit and forced to give up our own researches," he wrote. (Yoshimura 1984: 311) "The place seemed to be a hell. I felt most enormous pain to stay there. I bemoaned to the Heaven and the Earth." (ibid.: 314)

This explanation is perplexing, because he made brilliant achievement in physiological studies there, and even after the war he was very proud of it. Actually he wrote, "what let us narrowly keep staying in such a hell was that it was fairly free to perform animal experiments and hygiene studies in Manchuria. If there was no problem, we could publish our research outcome in academic societies in Manchuria and Japan." (ibid.) Because Yoshimura had both excellence and enthusiasm in research, this good scientific environment might be very reason to remain at Unit 731.


Dr. YUASA Ken, now 91 years old, worked for Luan Army Hospital from 1942 to 1945. He participated in 7 deadly group surgical trainings and vivisections, committing murders of 14 Chinese victims in total. These were purportedly trainings for newly assigned army surgeons to treat wounded soldiers at the front lines. These kind of group surgical trainings were performed many times in many places in China at that time. Yuasa's case is only one example.

Yuasa entered army in October 1941, about 6 months after graduation from Tokyo Jikeikai Medical University. He had training in Hokkaido for 2 months and became army surgeon. In January 1942, he was sent to Luan (now called Changzhi). He had his first deadly group surgical training in the middle of March of 1942, in which two Chinese men suspected to be spies and arrested by Japanese military police were murdered. He recalls the moment when he was ordered to participate in it:

When I was told that, I felt tense and thought, "Ah, this is it." It was whispered among students in my schooldays at Jikeikai Medical University that an army surgeon sent to China risked having to perform vivisection. Students knew that most of those who became army surgeons and went to China did it. Since I became an army surgeon, I recognized that I couldn't escape from it. (Yoshikai 1996: 65)

The order was issued by the First Army in North China at Taiyuan to army surgeons of each army hospitals, divisions, and brigades in its district. Yuasa writes everybody in the army hospital, even Chinese coolies, seemed to know that surgical training was performed on living Chinese. He describes:

In the dissecting room, every army surgeons talked and laughed each other. No one seemed to reflect nor be annoyed about poor Chinese men and direness of vivisecting humans. . . . I tried to appear calm, thinking inwardly that as an officer I must not seem to be coward, especially before soldiers. (ibid.: 71-72)

But as he experienced such vivisections again and again, he was getting used to perform them. In April 1944 he became vice director of Luan Army Hospital. He received secret order from the headquarters of the Army in North China in Beijing to perform group surgical training more frequently. So he made a plan to perform it 6 times in a year, which was admitted by the director and sent to the division of army surgeon in Taiyuan and Beijing. By force of circumstances, he actually directed 3 vivisections by the end of the war.


It's still hard to determine whether their decision to participate in medical atrocities was voluntary or not. Since there is neither complete coercion nor full freedom, it is a matter of degree. Here two comments can be made in interim conclusion.

First is on the hardness of order they had.
As Yoshimura was an Army Engineer, he was not under the strict military rules. He was ordered to go to Unit 731 by his own head professor, not by the Army. He has only conditional obligation, namely "if one don't want to give up his academic career, obey the professor." Actually he once cried desperately to Shoji that he would abandon physiology. So how hard he appealed his unwillingness to join Unit 731, the coercion he had was much weaker than the soldiers who was ordered to kill the enemy. Even if we don't regard it as a mere researchers' prudence, it was at best local obligation in academic society.

On the other hand, since Yuasa was professional army surgeon and the 'training' was according to military orders, he would be faced court-martial if he had refused to participate. Of course he could refuse if he outbraved it. But surely Yuasa had less room to refuse than Yoshimura, though he himself felt scant resistence then.

Second is on determination of contents of action.
No matter how badly Yoshimura insisted that he could not refuse to go to Unit 731, he was fairly free to determine ways of experiments, namely its purposes, methods, subjects, and so on. He had not been ordered how those experiments to be performed. Therefore he definitely had responsibility for torturing subjects by freezing. He can never justify his performance of cruel experiments by showing being sent to hell Unit against his will.

By contrast, Yuasa was ordered to perform deadly group surgical trainings by the headquarters. As it had become already common to use Chinese captives for these trainings, it must be impossible to plan trainings without vivisection. Or he would face court-martial. Even though he regard himself as completely guilty, he could only determine frequency of training and the number of subjects even when he could plan them by himself. Still he has responsibility because he can refuse the order regardless of facing court-martial. But he seemed to have far less room than Yoshimura in terms of committing cruelties.

Nevertheless, Yuasa is far more honest and sincere in reflecting his crime than Yoshimura. Being accused of war crimes made Yuasa's attitude different from that of Yoshimura and other doctors participated in medical atrocities. To the question why so few army surgeons confessed their crime of vivisection, Yuasa answers people forget what they want to forget. When Yuasa returned Japan and asked about vivisection to his former colleagues who escaped accusation, they had forgotten their own gruesome deed. But Yuasa and others who once recognized clearly their crime in Chinese prison cannot forget it. Thereby, they say, "we restored our own humanity."

Now Japanese government seems to wait these atrocities being forgotten. But in order to "restore humanity" of the country, we must remember them. We must not forget them, in order to keep on being human, who can make self-determination in the true sense.


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