Both opponents and proponents of Singer's right to speak about euthanasia have concentrated on the tenability of his claims. They have ignored the question of what legitimate grounds there are for suppressing academic discussion, and have failed to take into account the discussion of freedom of speech in recent legal theory. To do this is the aim of my paper. Section I claims that Singer's position is immoral. Section 2 turns to the question of whether it is protected by freedom of speech, irrespective of its merits. I reject two lines of defence for Singer's opponents, that they had no opportunity to present their case, and the Kantian idea of the primacy of practical reason. Section 3 turns to a defence from legal theory. It argues that Singer's views do not pose the kind of threat to other legal and moral values which would license a suspension of his freedom of expression. I conclude that it is illegitimate to silence Singer, since he does not deny the right to live of his disabled opponents, but legitimate to protest against him, since he denies that some of their lives are worth living, in disregard of their own preferences.