The need to protect the universality of science
In this article, Colin Blakemore and colleagues from the University of Oxford argue that the threshold needed to justify such a boycott must be extremely high. They also note that the International Council for Science explicitly forbids such discrimination.
Scientists have the same rights as other citizens to oppose policies of which they disapprove, they say. But they must not be used as pawns in political activity. And although there might be extraordinary circumstances that justify discrimination against scientists of a given citizenship, careful deliberation and collective judgement are needed to define them.
Link to Nature article
Reference: Nature 421, 314 (2003)