The officer who is to review the circumstances militating for and against detention and to decide, by reference to legal criteria, whether there are reasons to justify detention and to order release if there are no such reasons must satisfy certain conditions providing a guarantee to the person detained against any arbitrary or unjustified deprivation of liberty. Thus, the “officer” must be independent of the executive and of the parties. In this case applicant was deprived of liberty by a decision of a prosecutor who had not been a judge or other officer authorised by law to exercise judicial power. Furthermore, an arrested or detained person is entitled to bring proceedings for the review by a court of the procedural and substantive conditions which are essential for the “lawfulness” of his or her deprivation of liberty. The procedure must have a judicial character and provide guarantees appropriate to the kind of deprivation of liberty in question, in particular, in the proceedings in which an appeal against detention order is being examined, “equality of arms” between the parties must be ensured. Domestic law on control of mail of prisoners must indicate with reasonable clarity the scope and manner of exercise of the relevant discretion conferred on the public authorities so as to ensure to individuals the minimum degree of protection to which citizens are entitled under the rule of law in a democratic society.