Science can help to shape politics, the banner says: 'castration of science means impotence of Russia'. Credit: M. JAPARIDZE/AP

From time to time, groups of scientists propose a boycott of researchers who are citizens of another country, as a political protest against that country's government. It is not widely known that such discrimination is explicitly forbidden by the International Council for Science (ICSU, http://www.icsu.org) as contrary to the principle of 'universality of science'. (See also Nature 417, 690; 200210.1038/417690a for a statement by the International Human Rights Network of Academies and Scholarly Societies.) ICSU includes nearly 100 national academies of science and research councils, and 26 international scientific unions. We believe that these constituent organizations should do more to make their members aware of the universality of science as a central axiom of scientific conduct. We also suggest that the principle should be taught in graduate training, and accepted as the norm for all scientists.

ICSU's fifth statute describes universality of science as follows: “This principle entails freedom of association and expression, access to information, and freedom of communication and movement in connection with international scientific activities without any discrimination on the basis of such factors as citizenship, religion, creed, political stance, ethnic origin, race, colour, language, age or sex.” Although this statement contains some imperfections in wording that we should like to see clarified, its prohibition against discrimination on the grounds of citizenship is clear and unambiguous.

Nevertheless, it is obvious that universality of science cannot be an absolutely inviolable imperative. To take an extreme example, suppose that an international boycott of diplomatic, trade and cultural contacts were declared against a rogue regime as the only way to avoid nuclear war. Would not most scientists agree that a boycott would be acceptable?

Might there be less extreme circumstances in which it would be proper to boycott scientists, or to discriminate against them in some way? In answering this question, it is essential to consider that science is potentially beneficial to everyone; that the value of a scientific discovery is independent of the discoverer's characteristics; and that the continued ability of scientists to cooperate and transcend boundaries is an important symbol of, and impetus to, the breakdown of political divisions.

To expand on this last point, free communication of information and ideas has historically been significant in the liberalization of autocratic regimes — for example, it was a factor leading to the end of totalitarian regimes in Eastern Europe. Authoritarian governments try to suppress the flow of information and ideas, and to control the participation of their citizens in international activities. The task of scientists in other countries is surely not to exclude their colleagues who live under such regimes from international contacts, but rather to draw them into dialogue.

An objective approach

Scientists can cooperate even when they belong to states in dispute. For instance, scientists from China and Taiwan attend international meetings together and usually interact on the friendliest of terms. Such contacts, which make an important contribution towards reducing hostility, are readily formed by scientists, because science aspires, however imperfectly in practice, to relative freedom from emotional content.

For all these reasons, we conclude that the threshold needed to justify a boycott of scientific colleagues elsewhere must be extremely high, fulfilling the following conditions. (1) The circumstances are exceptional, and the boycott is undertaken only after considered and careful scrutiny by scientists internationally, leading to an explicit judgement that it is worth abandoning the principle of universality of science on this occasion for a particular, overwhelming gain. (2) A boycott is not merely a political gesture but an action that would help to change the unacceptable behaviour of a regime. (3) Revulsion against a regime, and a belief in the necessity for exceptional measures against it, are so nearly universal that a boycott would be widely respected. (4) The proposed boycott is part of an internationally agreed programme of measures that express collective horror against a regime and are necessary to avert some foreseeable disaster.

Consider three examples to clarify these points. In the first, scientists in one country have asked their colleagues elsewhere to boycott them to put pressure on their government. It may be altruistic for scientists strongly opposed to their government to sacrifice their own interests for a deeply felt cause, but they are not entitled to sacrifice the interests of their compatriots. Moreover, the request of a group of scientists in one country is not decisive.

In the second, Dr X is known to have been personally involved in actions that violate human rights. Is it appropriate to impose a boycott on him? To boycott X in response to his own actions does not contravene the universality of science: its appropriateness depends on the circumstances and on the strength of the evidence against him. Anyway, X's actions do not justify a boycott of his compatriots.

Dr Y, writing from a military address in a country that has used chemical weapons against its own citizens, asks for information or materials for use in studying the spread of infectious disease. Are we justified in refusing Y's request? The development of bacteriological weapons contravenes international protocols. If we have good reason to believe Y might be involved in such development, we are both entitled and obliged to refuse the request. But we are not thereby free to discriminate against Y's compatriot who writes for information about an innocuous topic.

Scientists have the same rights as other citizens to oppose policies of which they disapprove by any legal means. They can also seek, within the law, to persuade colleagues elsewhere to protest against a particular government. What the principle of universality of science seeks to prevent is the use of scientists as pawns in political activity. Although there might be extraordinary circumstances that justify discrimination (including boycotts) against scientists of a given citizenship, careful deliberation and collective judgement would be needed to define them.

This article grew out of a series of meetings of the four of us, convened and chaired by M.Y. Our full report can be found at http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v421/n6921/full/421314b_fs.html.