A/HRC/35/31 96. The main role of judges when facing such situations is to permit the detainee to challenge the legality of the arrest and detention before a court of law. Judges must not only decide about the lawfulness of the detention; they have also to ensure that the person’s fundamental rights have been respected. Right of access to a lawyer 97. Any detainee or accused person has the right to have access to a lawyer without undue delay. It is the obligation of States to set out the necessary mechanisms to ensure that persons deprived of their liberty can effectively exercise their defence rights, including the access to a lawyer. 98. The United Nations Principles and Guidelines on Access to Legal Aid in Criminal Justice Systems stipulate that legal aid is an essential element of a fair, humane and efficient criminal justice system that is based on the rule of law. 99. Such a right is paramount in a State based on the rule of law. It guarantees the possibility for the detainee to rebut the evidence presented against him or her and act in the most favourable way for his or her interest. Military courts and the right to a fair trial 100. Military courts tend to be structured within a hierarchical system of command and control. This creates a difficulty in conducting a fair and impartial trial. Military procedures carried out or influenced by corrupt officers create a general distrust in military courts on the part of civilian populations, as stated by Arne Willy Dahl at an expert consultation organized by the Office of the United Nations High Commissioner for Human Rights in 2014 (A/HRC/28/32). Such situations of bias and corruption result in a violation of article 14 of the International Covenant, which stipulates that everyone shall be entitled to a fair and public hearing by a competent, independent and impartial tribunal established by law. 101. The Special Rapporteur calls on States to adopt specific norms that expressly exclude civilians from investigation and prosecution by military tribunals, ensure that their jurisdiction is limited to military offences committed by active members of the military and protect the rights to fair trial and due process. Role of the justice sector in states of emergency 102. States are responsible for providing effective domestic remedies before independent and impartial courts or authorities. Non-derogable rights must be protected in states of emergency, and under no measures of derogation should the efficacy of these remedies be allowed. As clarified by the Human Rights Committee in its general comment No. 29 (2001) on derogations from provisions of the Covenant during a state of emergency, even if a State party, during a state of emergency, and to the extent that such measures are strictly required by the exigencies of the situation, may introduce adjustments to the practical functioning of its procedures governing judicial or other remedies, the State party must comply with the fundamental obligation, under article 2, paragraph 3, of the Covenant to provide a remedy that is effective. 103. According to article 14 (1) of the International Covenant, in the determination of any criminal charge against them, or of their rights and obligations in a suit at law, everyone shall be entitled to a fair and public hearing by a competent, independent and impartial tribunal established by law. As indicated by the Human Rights Committee in its general comment No. 32 (2007) on the right to equality before courts and tribunals and to a fair trial, derogating from normal procedures required under article 14 in circumstances of a public emergency should ensure that such derogations do not exceed those strictly required by the exigencies of the actual situation. The guarantees of fair trial may never be made subject to measures of derogation that would circumvent the protection of non-derogable rights. Deviating from fundamental principles of fair trial, including the presumption of innocence, is prohibited at all times. 16