The freedom to criticise government, and even to counsel disobedience or revolt, is widely considered the principal mark of a free society. Where the dissident voice is silenced by laws against sedition, it has been argued, there is no genuine freedom of speech and, accordingly, no real political freedom.2 The force of this suggestion stems from the underlying idea that government, if constitutional and legitimate, should be government by consent: laws against sedition, or which otherwise curtail political debate in order to silence opposition, repudiate that idea by denying the legitimacy of dissent.