The disease poses a grave and fast-moving threat to every nation. Governments have, quite reasonably, assumed emergency powers to counter it. But such powers can be abused. Governments have selectively banned protests on the grounds that they might spread the virus, silenced critics and scapegoated minorities. They have used emergency measures to harass dissidents. And they have taken advantage of a general atmosphere of alarm. With everyone’s attention on covid-19, autocrats and would-be autocrats in many countries can do all sorts of bad things, safe in the knowledge that the rest of the world will barely notice, let alone to object.