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Unit 731 and moral repair
  1. Doug Hickey,
  2. Scarllet SiJia Li,
  3. Celia Morrison,
  4. Richard Schulz,
  5. Michelle Thiry,
  6. Kelly Sorensen
  1. Department of Philosophy, Ursinus College, Collegeville, Pennsylvania, USA
  1. Correspondence to Dr Kelly Sorensen, Department of Philosophy, Ursinus College, 610 East Main Street, Collegeville, PA 19426, USA; ksorensen{at}


Unit 731, a biological warfare research organisation that operated under the authority of the Imperial Japanese Army in the 1930s and 1940s, conducted brutal experiments on thousands of unconsenting subjects. Because of the US interest in the data from these experiments, the perpetrators were not prosecuted and the atrocities are still relatively undiscussed. What counts as meaningful moral repair in this case—what should perpetrators and collaborator communities do decades later? We argue for three non-ideal but realistic forms of moral repair: (1) a national policy in Japan against human experimentation without appropriate informed and voluntary consent; (2) the establishment of a memorial to the victims of Unit 731; and (3) US disclosure about its use of Unit 731 data and an apology for failing to hold the perpetrators accountable.

  • Chemical and Biological Weapons
  • Codes of/Position Statements on Professional Ethics
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Mengele and the Jewish prisoners in Nazi concentration camps—that is the most familiar moral nadir in wrongful human medical experimentation, at least in the USA and Europe. Many also know about the Tuskegee syphilis experiments performed on 600 black men in the USA from the 1930s through the 1970s. Less familiar are the activities of Unit 731, a biological warfare research organisation that operated under the authority of the Imperial Japanese Army in the 1930s and 1940s. Unit 731 vivisected hundreds of human subjects. Others were intentionally infected with disease, deprived of food and water for the purposes of collecting data about time to death and staked as human targets for weapons testing. Thousands of others died from the testing of fleas weaponised to spread the bubonic plague.

After the commission of these deep moral wrongs, what should the perpetrator community do? What counts as moral repair—what counts as appropriate acknowledgement, apology, reparation and redress, especially for wrongs that cannot ever be fully repaired? The difficulty of these questions is compounded by differences among cultural norms about moral wrongs and moral repair for those wrongs. We propose a way forward. First, we should examine what victim communities are asking for by way of moral repair, since victim communities are specially situated epistemically with regard to the harm done to them.i In the absence of surviving Unit 731 direct victims, we look to victims from the same era who also suffered grave wrongs. There may be no univocal view among these victims, but we may detect some common themes and patterns. Next, we should look at what perpetrator communities ask by way of moral repair when they have been victims of comparably grave moral wrongs; we can then ask for consistency here—what they ask when they have been victims is reasonable to demand of them as perpetrators, guided by what their own victims want. Finally, we can look for moral repair resources in practices already in place in the perpetrator community.

We will apply this approach in the specific case of Unit 731. We will examine what two sets of Chinese and Korean victim communities ask in moral repair regarding the Pacific War.ii Next we will turn to types of moral repair that Japan has requested with respect to the US bombing of non-combatants in Hiroshima and Nagasaki. We will endorse three specific near-term, non-ideal, but substantive forms of moral repair.

Unit 731 and the ethics of human experimentation

By 1936, the Japanese Imperial Army had appointed Ishii Shiro as the chief of a water purification bureau in Manchuria. Known for a water filter he had invented, Ishii used his position to catalyse military interest in biological weapons research. Ishii's specific unit had been given a numeric designation—‘Unit 731’—for additional secrecy by 1941. Ishii and his team of researchers, in facilities in Manchuria, China, Thailand and Singapore, pursued their aims through relentless human experimentation. Over 3000 human subjects died in Unit 731's Ping Fan compound in Harbin alone, and thousands more were killed by Ishii's collaborators in other biological weapons facilities. Most of the victims were from Manchuria, delivered to Ping Fan by the occupying Japanese police force, who claimed their captives were criminals and political activists. Allied and Russian prisoners of war were also among the victims. So were children. The victims were subjected to both field and in-house experiments, including live dissection without anaesthesia, intentional infection with diseases and the subsequent removal of infected organs while still living, exposure to the testing of germ bombs that were intended to spread the Bubonic plague and injection with animal blood. Some were tied to poles while hit with flamethrowers, grenades and experimental biological warfare weapons. The list of conditions studied on unwilling human subjects is alarming: plague, cholera, glanders, anthrax, smallpox, dysentery, tuberculosis, typhoid, tetanus, frostbite and gangrene.1–3

For a variety of reasons, information concerning Unit 731's experiments on human subjects has been slow to emerge. Not least among the reasons was the USA's attempt to procure Unit 731's data at the end of the Pacific War. In exchange for some of Unit 731's findings, the USA apparently granted immunity from Tokyo Trial war crimes prosecution to various Unit 731 leaders. The use the USA made of the data remains largely undisclosed.

We argue that Unit 731 committed deep and important moral wrongs. But some may object that retrospective and cross-cultural moral judgements of this sort are not possible, because this means holding people to our contemporary moral standards—standards people in the past and in different cultures did not necessarily share. This objection is difficult to sustain. First, nearly everyone believes that American slavery was morally wrong and was wrong for the people who practised it in its time, even though considerable cultural differences separate people in the early 21st century from that time period. To deny that retrospective moral judgements are reasonable means denying that even this judgement about American slavery is reasonable. Second, Imperial Japan was well aware of the 1925 Geneva Protocol, an international ban on chemical and biological weapons. Those involved with Unit 731 knew they were violating a clear global consensus against these weapons.iii Third, the obsessional secrecy surrounding Unit 731 facilities and documentation suggests that those involved knew they were committing moral wrongs. It may be objected that the obsessional secrecy shows not that those involved believed what they were doing was wrong, but instead only that secrecy was important for strategic military reasons, or merely that participants believed others elsewhere would mistakenly disapprove. But other evidence, including what Ishii Shiro had to do to get government approval and funding, and the way Ishii and other Unit 731 participants discussed the experiments on humans, suggests an awareness of complicity in deep moral wrongs. At the Ping Fan Unit 731 location opening, Ishii said this to his research workers:Our god-given mission as doctors is to challenge all varieties of disease-causing microorganisms; to block all roads of intrusion into the human body; to annihilate all foreign matter resident in our bodies; and to devise the most expeditious treatment possible. However, the research work upon which we are now about to embark is the complete opposite of these principles, and may cause us some anguish as doctors. Nevertheless, I beseech you to pursue this research…5

Many Unit 731 participants may have thought of Chinese and other non-Japanese experiment victims as inferior, but it took socialisation—sometimes brief, sometimes sustained—to get them to think of vivisecting victims as morally permissible.6 Fourth and finally, making retrospective moral judgements and holding accountable participants in past atrocities help deter similar moral wrongs in future. For these reasons, retrospective moral judgements are defensible. There are sufficient shared moral understandings among perpetrators and victims in order for moral repair to be both plausible and necessary.7 ,8

Elements of moral repair

First-order moral questions—questions about what is right and wrong, morally permissible and impermissible—are central in moral evaluation. But second-order moral responses to these first-order matters are important as well. We will call a select set of second-order responses (acknowledgement, apology, reparation and redress) practices of moral repair. As Margaret Urban Walker argues, moral repair is essential to the sustainability of broader moral practices and the fabric that unites them.8 In this section, we articulate and defend some theoretical machinery relevant to our analysis.

Consider first a simple standard case. A backpacker is hiking in the high mountains when a freak storm strands him in deep snow. He comes across an unoccupied cabin. Desperate to survive, he breaks into the cabin for shelter and creates a fire from some furniture inside. Uncontroversially, the backpacker's action is morally permissible—the preservation of his own life is more important than the property rights of the cabin owner. Nevertheless, when he is safely out of the storm, the backpacker should perform moral repair: he should apologise, and he should compensate the owner for the damage done. This seems clear, whether we read the case in a consequentialist way, or instead, as the case's originator Joel Feinberg did, as an instance of an innocent and permissible infringement of a right, rather than a non-innocent violation of a right.9

  1. One aspect of moral repair in this simple case concerns its targets. The cabin is an obvious target of moral repair—it is what was broken, and it is what the financial compensation is intended to fix. More abstractly, we might think that another target is the moral constraint about respecting property. We might think that not only the cabin property, but the moral constraint against appropriating property was also damaged in some sense, such that the constraint itself needs some repair—and also that the backpacker's apology and compensation do something to repair and restore this constraint. The thought is that not only the physical cabin, but the moral constraint that protects the cabin as property, can need preservation and repair.iv

  2. A second aspect of moral repair is its addressee(s)—the cabin owner, where the target is the cabin. Who are the addressees if the target is the moral constraint itself? We might think it is the broader community: the agents who abide by the moral constraint.

  3. A third aspect is moral repair's expressive means. We suggested two common and important expressive means for the backpacker, and of course there are many others. An apology is one expressive means directed at the addressee about the target(s). Compensation is also an expressive means, again aimed at the addressee about its target(s). If the financial compensation is insufficient to repair the cabin, moral repair fails, and it will be relatively clear when and why it fails. Moral repair failure in the expressive means of apology is far more complex, since much can go wrong both on the side of the one apologising (insincerity, vagueness, clumsiness of expression, etc) and on the side of the addressee (misunderstanding, recalcitrance, refusal, etc). Some think that moral repair fails unless the addressee takes it to succeed; others believe that in at least some cases moral repair can succeed even in the absence of addressee uptake.v

  4. Finally, moral repair has a source. In the cabin case, the backpacker is the source, since he makes the apology and pays the compensation. If instead a third party acted on the backpacker's behalf, that third party would be the source. We might think of punishment as a broad kind of moral repair that involves a third-party source: on some views of punishment, the state undertakes moral repair on behalf of victim addressees, forcing perpetrators (some unwilling, and some willing and so also themselves sources) to undertake various expressive means. For instance, the USA should have, but did not, hold the Unit 731 perpetrators accountable; and this moral repair failure itself calls for moral repair, as we will proceed to argue.

We will use these four terms—target, addressee, expressive means and source—as technical terms below.

Moral repair and non-Japanese victim communities

Let's turn to more complicated cases that show what real victim communities ask for by way of moral repair. Victim voices are important, since victims are in a special epistemic situation: they have distinctive first-person experience in suffering grave wrongs. The moral authority that comes from this epistemic position should guide what counts as adequate moral repair. Since no direct victims of Unit 731 survived, we should look to victims who suffered comparably grave wrongs in the same era and the same wartime conflict. Victims of grave wrongs from other eras and conflicts may concur; but given the contextual complexities of mass killings, it is methodologically prudent to listen primarily to same-era, same-conflict victims. The common themes and patterns that emerge will help arrive at some conclusions about moral repair.

In the 1930s and 1940s, Imperial Japan's military provided its soldiers with ‘comfort women’, a euphemism for women kept in sexual Tens of thousands of these women, most often from occupied Korea, were forcibly abducted or tricked by promises of employment as nurses, laundrywomen or factory workers. Unlike breaking into the cabin, sexual slavery was not morally permissible. In Feinberg's terms, the rights of these women were wrongfully violated, not permissibly infringed.9 Moral repair is accordingly more important and weighty here.

Unlike the cabin case, it was the comfort woman herself who was violated, so she is simultaneously a target and an addressee, since it is her will and her body—her—on which the wrong was wrought. Another target, the moral constraint against abduction and sexual slavery, involves multiple addressees: the women, the broader global human community and possibly Korea as a collective. This last addressee is new and complicated for a variety of reasons. One complication is historical: Japan's (so far inadequate) attempts at moral repair regarding comfort women have tended to concern South Korea; but of course there was no South Korea during the Pacific War—North Korea and South Korea are inventions of the 1953 armistice—and women from what is now North Korea functioned as sex slaves as well, as did women from other areas in Asia.16 Another complication involves group identity, group membership and nationality, and the controversial view that there are group rights and nationality rights: how must we conceive of groups if they are to be proper addressees of moral repair?

The candidate expressive means in the comfort women case are many and contested. They include acknowledgement, expressions of regret, apology and financial compensation. Financial compensation is a fraught expressive means. In the cabin case, what was damaged can be straightforwardly fixed with commensurable replacements. But there is no clear commensurability between abduction and sexual slavery on the one hand and financial compensation on the other hand. Accordingly, some addressees find financial compensation inappropriate and insulting. But other addressees endorse it, not because they think money can commensurate with abduction and sexual slavery, but variously because it can represent a substantive sacrifice on the part of the morally repairing sources, because it is more difficult to take back than an apology, and/or because even though money and sexual slavery are incommensurable, the surviving comfort women, economically insecure for most of their lives (in part because of the stigma of their past as comfort women) and now old, nevertheless benefit—compensation does in some way give them the economic security their status as sex slaves took from them.13 Formal political apologies, another candidate expressive means, can be so weak that addressees have reason to find them insufficient. In the Kono Statement in 1993, Japan's Chief Cabinet Secretary, Kono Yohei, admitted that comfort women were indeed taken against their will. He stated that the country does apologise; however, his statement was not an official statement; and in any case he said that only the military, not the government, was involved, and only to a limited extent. Formal political apologies can also have a short shelf life. In 2006, Deputy Chief Cabinet Secretary Shimomura Hakubun argued against the legitimacy of the Kono Statement, expressing his doubt in the Japanese military's use of comfort women. Because of these complications in expressive means, Japan's past moral repair concerning comfort women has failed. Addressee uptake, especially among the surviving women themselves, is almost non-existent; and it is reasonable in this case to take the women addressees as the authorities about whether moral repair has been at all successful.

The issue of source is complex in this case as well. Many surviving Korean comfort women, the addressees who are most known and vocal, want the source of moral repair to be the Japanese government. Instead what emerged in the 1990s, when the spotlight fell on comfort women, is the Asian Women's Fund, which offered financial compensation to surviving victims. But many of the women and their supporters criticised the fund, because a substantive amount of the money came from private donations, not from the Japanese government itself. Put simply, the addressees argue that the source of moral repair in this case is inadequate to count as genuine, successful moral repair.13

The governments of Japan and South Korea announced an unexpected agreement about the comfort women case in December 2015. This time the Japanese government is offering financial compensation from its own national budget, thus more nearly satisfying the issue of moral repair's source. But the victim community is still concerned that the addressee of the agreement is the South Korean government and political expediency, and not so much the comfort women themselves. No comfort women were part of the negotiations. Further, the expressive means of the agreement is inadequate because it still leaves vague the nature of responsibility the Japanese government is taking and falls short of legal reparations. Third, the agreement encourages the removal of a memorial, a statue of a young comfort woman, currently in front of the Japanese Embassy in Seoul—something the victim community strongly resists. This memorial, like the Harbin museum at the ruins of Unit 731's primary site in northeastern China, was erected by the victim community. Victim communities want their experiences memorialised—permanently. A particularly powerful expressive means of moral repair would be the creation of a memorial by the perpetrator community: imagine the meaningfulness to the victim community if, for instance, the Japanese government and its citizens welcomed this statue, or created one like it, on Japan's mainland. Instead, the December 2015 agreement aims to end and silence future discussion about the comfort women by the two governments.17

As we noted above, thinking about moral repair is made especially difficult by differences among cultural norms. But we have already taken a step in addressing this issue: our discussion of the comfort women looks to articulations from a victim community—a victim community from the same era and from the same wartime conflict—about the kind of moral repair they want. The Unit 731 victim community has been less visible than the comfort women, because there are no known survivors from in-unit human experimentation, and only victim families and those coerced to work in Unit 731 facilities are left to speak.18 But there are survivors of another stage of experimentation: those in China who were subject to Japan's attempts to weaponise the bubonic plague based in part on what had been learnt by Ishii and his researchers. Activist Wang Xuan sued Japan in behalf of 180 Chinese victims of biological weapons. In 2005, the Tokyo High Court rejected the group's demands for an apology from the Japanese government and compensation. But the High Court did let stand a lower court's admission that Unit 731 existed and “used bacteriological weapons under the order of the imperial Japanese Army's headquarters.”19 ,20 And the Chinese government has demanded that Japan clean up chemical weapons buried in the region of the Unit 731 compound.

Two important repeated themes here are (i) moral repair's source and (ii) expressive means with permanence: both the comfort women and the victim community in China want substantive moral repair to come from the Japanese government itself, and they want permanent memorials and chemical weapons cleanup.

Moral repair and Japanese victim communities

Another strategy for dealing with the difficulties of cultural norm differences looks at what perpetrator communities ask by way of moral repair when they have been victims of comparably grave moral wrongs. We will then ask for consistency here—what perpetrator communities ask when they have been victims is reasonable to demand of them as perpetrators, guided by what their own victims want. What requests for moral repair are there among Japanese writers for the intentional killing of tens of thousands of non-combatants in Hiroshima and the firebombing of Tokyo?

The atomic bomb that the USA dropped on Hiroshima, Japan, on 6 August 1945, killed tens of thousands of non-combatants immediately and tens of thousands more from injuries and radiation sickness over the months that followed. Three days later, many thousands more non-combatants were killed by a second bomb in Nagasaki. The USA provided no advance warning so that non-combatants could evacuate, and the USA did not demonstrate its new weapon in alternative ways, such as in some uninhabited area in Japan. And in any case, the USA did not need to demand unconditional surrender; a conditional surrender could plausibly have been negotiated, with many lives saved.21 Further, Japan might have surrendered anyway when, as the USA expected, the Soviets attacked Japan on 8 August 1945.vii This mass killing of Japanese civilians was morally impermissible; it cannot be counted as permissible collateral damage even in a just war. Other aspects of the bombing, including the use of different bomb technologies in Hiroshima and Nagasaki and the US subsequent monitoring of survivors, show that human experimentation was going on here, too.

What would count as appropriate moral repair in this case? There are many candidates, including a formal apology from the USA for the use of nuclear weapons on civilians, or more modestly whatever acknowledgement was implied by photos of the victims at the proposed 1995 Enola Gay exhibit—photos that were unfortunately removed in a controversy before the exhibit opened. The USA has not performed moral repair of this past-directed sort, despite requests for acknowledgement and apology from various organisations in Japan. But the dominant demand for moral repair in Hiroshima's Peace Park is instead future directed—a demand for the elimination of nuclear weapons, so that similar atrocities do not happen again. This request is expressed in various ways through the Peace Park, including in the famous quote at the Memorial Cenotaph, which vows that ‘…we shall not repeat the error’ of using nuclear weapons. (Radhabinod Pal famously asked to whom ‘we’ in the English translation of the cenotaph inscription refers; a later plaque was added to clarify that ‘we’ means all of humanity.) It was also the dominant theme expressed by the atomic bomb survivor who spoke with the six of us about her life, and about moral repair, at the Hiroshima Peace Park in June 2014. The bombing victims—the addressees of moral repair here—ask for the international abolishing of nuclear weapons as the expressive means; the source of the moral repair here is not just the USA, but all nations who have (or are seeking to create) nuclear weapons, and the target is both the victims themselves and the constraint against direct killing of non-combatants.

The international abolishment of nuclear weapons is of course an extremely ambitious kind of moral repair. One might think of it as ideal moral repair, coupled with past-directed acknowledgement and regret from the USA for bombing Hiroshima. In the case of Unit 731, ideal moral repair, with a similarly ambitious and broad moral scope, would involve the international abolishment of wrongful human experimentation, both in national and international policies and in fact. Ideal moral repair may best satisfy addressees, but it is of course extremely difficult to achieve. Organisations such as Mayors for Peace, organised in 1982 by Takeshi Araki, admirably work towards the complete abolition of nuclear weapons, for its own sake and for the sake of moral repair.

But non-ideal moral repair is important, too. Though short of the aim of Mayors for Peace, it would be non-ideal but nevertheless meaningful moral repair for the USA to apologise for the use of nuclear weapons on civilians. In the case of Unit 731, we want to argue for three non-ideal but immediately realistic forms of moral repair. We believe that all three are substantive, meaningful and overdue. All are informed by the elements of moral repair and the patterns of what same-era, same-conflict victims of comparably grave wrongs want, as discussed in previous sections. And all have the mark of consistency: they ask of the perpetrator community something consistent with what the perpetrator community itself asks elsewhere—including when they have been victims of comparably grave wrongs.

(A) The first kind of non-ideal moral repair is the establishment of an explicit government-issued national policy in Japan against human experimentation without appropriate informed and voluntary consent. Currently, there is no such policy. Other nations have policies of this sort. Such a policy need not directly address Unit 731's human experimentation. That is what makes it both non-ideal and politically feasible. It would be non-ideal because the policy would not need to explicitly acknowledge Unit 731 or connect the policy to the Imperial Japan period.viii But since the Liberal Democratic Party, Japan's dominant party over the last decades, has been extremely resistant to acknowledging and addressing past atrocities, little more than this seems possible at the moment.

It might be objected that such a policy is too non-ideal to constitute moral repair, since it would be only indirectly connected to the original human experimentation atrocities of Unit 731. But an explicit policy would achieve some real moral repair because it would have an important target: the affirmation and public endorsement of the constraint against the wrongful use of human beings in medical experimentation. The policy would achieve some moral repair because it would contribute to the sustainability of shared moral practices and the fabric that unites them.8 And the policy would achieve some moral repair even if, and all the more because, the policy only affirms what is already the standing current practice in medical testing in Japan. Formalising ethically sound medical testing should strengthen its status. An important aspect of affirming the constraint would be the Japanese government as the source of the policy. The current medical community in Japan should also explicitly endorse the policy, since the medical community collaborated with Imperial Japan in wrongful human experimentation, and after the war relocated Unit 731 doctors within the profession without penalty or stigma. Chinese and other addressee victims of the Unit 731 experiments will reasonably want more, but because of the source and at least one target (the moral constraint) of an explicit policy of this sort, it is substantive moral repair. Moral repair can be future-directed as well as past-directed. Atomic bomb survivors who speak at the Hiroshima Peace Park say that minimising the chance of future atrocities is an important goal and an important type of moral repair.ix And consistency matters here: a national policy against human experimentation gives the perpetrator community an opportunity to offer what it expects as a victim community.x

The absence of an explicit mention of Unit 731 in a national policy is non-ideal in some ways, but good in others: it helps avoid the political exploitation of apologies. The USA, Japan, South Korea and North Korea have at times used political apologies—both the apologies of others and their own—to further economic and political ends unrelated to the addressees of those apologies.14 A national policy against wrongful human experimentation is less vulnerable to political exploitation.

(B) A second kind of non-ideal moral repair we endorse is the creation of a permanent memorial, some dedicated physical object and space, that publicly acknowledges Unit 731's wrongful human experiments. As we saw in the case of the comfort women, political apologies can have a short shelf life; physical memorials are more lasting and less reversible. The source of moral repair in creating a memorial would ideally be the Japanese government, but until that is possible, Japanese citizens could fund and build the memorial themselves. Because it does not require government action, this sort of moral repair is particularly realistic and feasible; for one thing, surveys show that the Japanese population is usually far more willing to own up to past wrongs than the Japanese government.27 And there is precedent elsewhere for memorials created from other sources of moral repair than the government: Gunter Demnig's long-running ‘Stolperstein’ project, for instance, has installed tens of thousands of stones noting Holocaust victims, often in the location from which they were forcibly moved.28 In the spirit of the Stolperstein movement, Japanese citizens could install memorials about the comfort women and the victims of Unit 731. Governments are reluctant to officially apologise, among other reasons, to forestall a stream of financial compensation claims from victims and victim families; but independent citizen groups are in different circumstances. Independent Japanese citizen groups have already pushed their government for recognition of suppressed Imperial Japan wartime practices, such as the production of chemical weapons on Okunoshima, a small island in southwestern Japan, strategically left off maps for years. Ishii Shiro ordered materials for Unit 731 experiments from the Okunoshima facility.29 ,30 Surviving Okunoshima weapons factory workers have successfully pressed the Japanese government for treatment and compensation for injuries sustained in the development of these weapons, and in 1988, a museum opened on the island, stocked with donated items from families of the affected workers. Obtaining indirect recognition from the Japanese government is a small but important achievement that shows what citizen initiatives can accomplish.xi

We saw above that in the case of the comfort women and the expressive means of financial compensation, victim addressees were strongly dissatisfied with a non-governmental source of moral repair. But Gunter Demnig's Stolperstein movement shows that another expressive means, memorial creation by perpetrator community citizens, can offer substantive moral repair. Unit 731 and comfort women victim addressees may be more willing to accept memorial creation from a non-governmental source, if only as a first non-ideal step.

A key way to strengthen the moral repair work of a Unit 731 memorial would be to ensure that inscribed upon it are all known individual victim names. Unfortunately, the names of many victims are not known; but some are. Unit 731 researchers called their victims ‘logs’ and tracked them by number instead of name. In light of this particular kind of dehumanisation, an important and appropriate expressive means in moral repair is to make those individual names publicly known. We can again look to the Hiroshima Peace Park for more ideas—and crucially, ideas consistent with the wishes of Japanese atomic bomb victims: the Peace Park features narratives about particular individual victims, and a Unit 731 memorial would be wise to do the same. China has not waited for moral repair—as Hiroshima victims did, it has built a museum on the ruins of the Unit 731 facility at Harbin.xii But even non-ideal substantive moral repair should feature more initiative from members of the perpetrator community.

(C) Japan is not the only nation that needs to do moral repair. The USA, we and others33 believe, should also do moral repair because of its handling of Unit 731 at the end of the war. The evidence indicates that the USA offered immunity from prosecution in exchange for some of Unit 731's data; so while German doctors and scientists were prosecuted for war crimes, Japanese doctors and scientists were not. Intentionally omitted from the post-war Tokyo Trials, many Unit 731 leaders went on to have successful careers and the respect of the community, their atrocities hidden and unknown. Victims and victim families of Unit 731, unlike other victims of the period, did not see the atrocities publicly marked and the perpetrators held accountable. So public accountability for wrongful medical experimentation at the end of the Pacific War was either asymmetric or non-existent.xiii Some claim the USA's reason for exchanging prosecution immunity for data was to keep the data from the Soviet Union, and that overall this was expected to be for the greater good, because the Soviet Union would misuse the data and the USA would not. But it is important to note that the USA wanted not only to block others from getting the data; the USA wanted to use the data for its own biological weapons programme. US medical research at Fort Detrick in Maryland was apparently not performed on unwilling subjects, but US medical professionals studying biological weapons there very much wanted to learn what Japanese researchers had, through unscrupulous means, already discovered.xiv

What should the USA do? We believe that US presidential acknowledgement and apology is a plausible and consistent form of non-ideal moral repair for the USA in the case of Unit 731. This acknowledgement should also disclose how the USA has used the data.xv Besides Unit 731's victims, the target of this moral repair is a moral constraint against pardoning war criminals in order to obtain their ill-gotten data. It may seem that this asks more of the USA than we are asking of Japan, but we believe our position harmonises with the demands above. There are two reasons for this. First, the wrongs the USA committed with respect to Unit 731 are less severe than those committed by Imperial Japan, and so it is less politically damaging for the USA to formally acknowledge them. Failing to prosecute killers in exchange for their information is deeply wrong, but it is less wrong than the killing itself. Second, the USA already has a broader (though certainly very imperfect) track record of related apologies, and these apologies tend to have a long shelf life; what we are asking for is closer to standard practice in the USA. For instance, President Bill Clinton apologised in 1997 to the remaining survivors of the Tuskegee wrongful human medical experiments:The United States government did something that was wrong—deeply, profoundly, morally wrong. It was an outrage to our commitment to integrity and equality for all our citizens….To the survivors, to the wives and family members, the children and the grandchildren, I say what you know: No power on Earth can give you back the lives lost, the pain suffered, the years of internal torment and anguish. What was done cannot be undone. But we can end the silence. We can stop turning our heads away. We can look at you in the eye and finally say on behalf of the American people, what the United States government did was shameful, and I am sorry.xvi

Tuskegee survivors had received some financial compensation from the US government in the decades before this, but the expressive means of a presidential apology was still important regarding at least two targets: Tuskegee victims and victim families, and the constraint against wrongful human experimentation. A related expressive means is important in the case of Unit 731. Consistency tells us to look to what perpetrators demand when they are victims of comparably grave moral wrongs, and consistency with practices already present in the perpetrator community also matters; US presidential apology is a case of the latter. There are important disanalogies between Tuskegee and the Unit 731 case: for one, the USA was a direct perpetrator in the former and only involved after the deepest wrongs had occurred in the latter. Still, Tuskegee is a relevant place to look for standing practices in US moral repair.

The three forms of non-ideal moral repair we have argued for are comparatively modest. For instance, we have not argued for reparations and financial compensation to victims and victim families. As we saw in the case of the comfort women, some victims ask for financial compensation as an expressive means of moral repair, despite the incommensurability of deep moral wrongs and money. But given the reluctance of the Japanese and US governments to address past atrocities with full legal reparations, we argue for more immediately achievable expressive means of moral repair. An additional worry about financial compensation moral repair is this: not only may it do little to prevent future moral wrongs; it may make them easier to commit. Potential wrongdoers may see financial compensation as a ‘fee’ rather than as a ‘fine’ for the moral harms they carry out. When compensation is seen as a fee, it may be easy for researchers to believe that problematic human experimentation is not morally wrong, just financially expensive.

Political apologies are also vulnerable to the last concern, including the apology we ask of the USA about its involvement: we want the US government on the record about its role in Unit 731, but we do not want the USA and other nations seeing apologies as an easy excuse. Alexis Dudden notes that the first moral repair steps that sources make, especially government sources, can easily calcify into the last steps. Governments prefer to think they have fully completed moral repair with whatever formal acknowledgement they offer.14 So it is worth worrying about asking too little by way of non-ideal moral repair. But even with this worry in mind, we believe that, especially in the case of the particularly ignored atrocities of Unit 731, some modest first steps are better than no steps, and provide something victims and victim families can build on.


Both the obscurity of Unit 731 and the depth of the wrongs associated with it make moral repair especially important. We have endorsed and defended three concrete forms of near-term, non-ideal moral repair: (1) the establishment of a Japanese government-issued national policy against human experimentation without appropriate informed and voluntary consent, (2) the creation of a permanent physical memorial that publicly acknowledges Unit 731's wrongful human experiments and (3) US acknowledgement and apology regarding the obtaining and use of Unit 731's data. All three will require public pressure and activism from both victim and perpetrator communities. But activists can claim that moral repair is not only morally required, but also the mark of not weak but strong states. In this unfortunately unremembered case of wrongful human experimentation, respecting human subjects now and in future is strengthened by moral repair concerning the past.xvii


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  • Contributors All listed authors contributed to the content and writing of this paper.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • i By ‘victim community’, we mean those who were directly affected by moral wrongs and those in special relationship with them, such as families and co-nationals. By ‘perpetrator community’, we mean those who performed moral wrongs and those in special relationship with them, such as families and co-nationals. There are complications in defining these communities in the case of historical wrongs. Even the comparatively recent historical wrongs that we discuss above include complications about changing political regimes and new generations. The burdens and benefits of past moral wrongs fall on members of these communities; they need not inherit full responsibility and authority about past wrongs to inherit some responsibility and authority regarding moral repair.

  • ii We will use the standard term ‘Pacific War’ for the events in East Asia beginning with Japan's invasion of Manchuria in 1931 through Japan's surrender in 1945.

  • iii Some other nations signed and then violated the 1925 Geneva Protocol against biological weapons research.4

  • iv Michael Walzer discusses repairing violations of the moral constraint against targeting non-combatants in war in Just and Unjust Wars. See particularly Walzer's discussion of reasons for not honouring Arthur Harris, who oversaw British firebombing missions in Germany.10

  • v Compare promises: some think whether a promise exists depends on whether there is promisee uptake; some think otherwise.11 Whether addressee uptake is necessary for moral repair to be successful depends on the point and purpose of moral repair. If the point and purpose is the restoration of relationship, addressee uptake would be necessary. Nick Smith addresses a rich set of additional considerations about apologies beyond the key elements above.12

  • vi We prefer the more accurate term ‘sexual slaves’ for this practice; but since ‘comfort women’ has become a familiar term, and because it is the term most often used by the surviving women themselves, we tend to use the latter term above.13 ,14 Some Japanese nationalist defenders of the comfort women practice make consequentialist arguments for it: the practice was designed to control and minimise civilian rape by soldiers, which would have been worse in the absence of the comfort women. This argument is both empirically and morally suspect, so we will not take it seriously. Yu Bin offers a Jonathan Swiftian treatment of this argument.15

  • vii Jeff McMahan and others make this claim.22 Robert P. Newman and others think otherwise.23

  • viii Japan's legislature did acknowledge the existence of Unit 731 in 1982.24

  • ix In the case of comfort women, minimising future and present global sexual slavery would be a related expressive means of moral repair. This would require something more substantive than Japanese Prime Minister Junichiro Koizumi's 2001 nascent remarks: “Japan also should take an active part in dealing with violence and other forms of injustice to the honor and dignity of women.”25

  • x Takashi Tsuchiya notes the absence of a general policy in Japan about human subjects research.26

  • xi Okunoshima is one candidate location for a citizen-initiated memorial, given what Japanese citizens have already made happen there. Okunoshima workers and their families have additional reasons to show solidarity with Chinese victims. Murakami Hatsuichi, the first curator of the museum, told the New York Times, “Both poison gas manufacturing and the atomic bombing happened in Hiroshima prefecture during the war….My hope is that people will see the museum in Hiroshima City and also this one, so they will learn that we were both victims and aggressors in the war. I hope people will realize both facets and recognize the importance of peace.”31 ,32

  • xii The Unit 731 Museum in Harbin is, unsurprisingly, strongly critical of Imperial Japan. The Harbin museum also includes names and narratives of some individual victims. But unfortunately, the exhibits say little or nothing about the role of the USA in obtaining data from Unit 731 while not prosecuting Unit 731 perpetrators. An interesting feature of the Harbin museum relevant to moral repair is the museum's ‘Repentance Room’, which displays the confessions of some individual Unit 731 participants. Individual moral repair of this sort is of course also important and commendable.

  • xiii A US State-War-Navy (SWNCC) Coordinating Committee Task Force report from 1947 uncomfortably notes this: “Experiments on human beings similar to those conducted by the Ishii BW [biological weapons] group have been condemned as war crimes by the International Military Tribunal for the trial of major Nazi war criminals in its decision handed down at Nuremberg on 30 September 1946.”34

  • xiv An American from Fort Detrick on an investigative trip to Japan in 1947 reported that Unit 731 data were obtained “at the expenditure of many millions of dollars and years of work…Such information could not be obtained in our own laboratories because of scruples attached to human experimentation.” Even now remarkably little is publicly known about the data and what the USA did with it. Sheldon Harris, author of the best study in English of the history of Unit 731, was able to get access only to a limited number of documents concerning US use of the data.35

  • xv A plausible stronger view would ask that the USA officially vow not to put the Unit 731 data to further use. The Environmental Protection Agency made a statement like this in the 1980s over concerns about the use of Holocaust human experimentation data.36

  • xvi The full speech is available at a Center for Disease Control website.37 It is worth noting that on another occasion Clinton refused to apologise for Hiroshima: “The United States owes no apology to Japan for having dropped the atomic bombs on Hiroshima and Nagasaki.”38

  • xvii Our deep thanks to Matthew Mizenko for his help on this paper.

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