The right to a fair trial is equally a fundamental right that is actively protected in times of armed conflict by international humanitarian law. The starting point is Common article 3(1)(d) of the 1949 Geneva Conventions. This prohibits the passing of sentences and the carrying out of executions without previous judgment pronounced by a regularly constituted court, affording all the judicial guarantees which are recognized as indispensable by civilized peoples. In addition, basic minimal guarantees are provided for in article 75(4) Additional Protocol I (relating to international armed conflicts) and in article 6(2) of the Additional Protocol II (relating to non-international armed conflicts).
With respect to possible derogations to fair trial guarantees in situations of armed conflict, the point of departure is that no derogation may be made from the relevant provisions of the Geneva Conventions or their Additional Protocols. Indeed, denial of the right to a fair trial can amount to a war crime in certain circumstances (General Assembly report A/63/223, para. 12). That said, there may be rare instances where a State may permissibly derogate from the fair trial clauses in the human rights treaties in question during an armed conflict (ICJ, 2004, para. 106).
In situations of armed conflict, international humanitarian law also guarantees the right and associated obligations of a fair trial (see e.g. Hamdan v. Rumsfeld, 2006). Generally, suspected terrorists must be treated as civilians for the purposes of their trial, which must therefore be governed by the international human rights principles and standards outlined in this Module. The exception is where the acts for which such persons are charged occurred in the context of an armed conflict when they were directly participating in the hostilities, e.g., employing prohibited terrorist methods, which should be governed by international humanitarian law. Unlike international human rights law, however, international humanitarian law does not specify any requirements or give details regarding practical aspects involved in prosecuting them such as necessary procedures or sanctions following a conviction. Furthermore, the overall length of time that a person is detained, including on suspicion of having carried out terrorist acts, can impact negatively on the right to a fair trial, especially if it is not subjected to appropriate period review by a judicial authority to ensure its continued necessity (General Assembly report A/63/223, paras. 21-22).
There are, however, important accompanying challenges ensuring such safeguards as fair trial rights and due process guarantees in practice during armed conflict situations. The United Nations Special Rapporteur on the independence of the judiciary and lawyers has made some interesting observations in this regard. In emphasizing the importance of "a basic set of rights that should be guaranteed, whatever the situation", the Special Rapporteur also reiterated the key role of the judiciary in "interpret[ing] the law and safeguard[ing] the constitution without any improper influences or pressures" whilst also noting that "in armed conflicts the threat to judicial independence is heightened, with threats both internal and external" (General Assembly, Human Rights Council report A/HRC/35/31, para. 107). Furthermore, whilst recognizing the special challenges faced by governments in balancing the protection of national security needs with those of individuals in armed conflict situations, nonetheless the Special Rapporteur concluded that "even if judges have to give greater weight to governmental interests that may be legitimate during times of war or severe internal strife, it is imperative for courts to control governmental power to guarantee the respect for the rule of law and the rights of citizens" (General Assembly, Human Rights Council report A/HRC/35/31, para. 108).