This paper inquires into whether the right to a fair trial can be restricted with regard to alleged terrorists within the framework of the ‘war on terror’. After briefly identifying the relevant sources of this right and its content, possible restrictions are analysed. The paper elaborates, in particular, on international humanitarian law, such as the Third and Fourth Geneva Convention, and international human rights law, such as the International Covenant on Civil and Political Rights and the American Declaration of the Rights and Duties of Man. It further deals with US constitutional law. We conclude that the right to a fair trial fully applies to alleged terrorists irrespective of the context of their detention (armed conflict or peace) or the qualification of these terrorists (de facto or unlawful combatants) and thus amounts to a general principle of transnational criminal law.