tion of the right to an effective remedy on account of the lack of a mechanism in domestic law that would have allowed the applicant to challenge the decisions to prolong his solitary confinement. Other examples where the right to an effective remedy has been violated include: • failing to provide adequate procedures to complain about, or obtain compensation for, killings by security forces; • not carrying out thorough enquiries into alleged ill-treatment by security forces; • not establishing complaints procedures regarding the interception of telephone calls. Retroactivity Article 15, ICCPR: 1. No one shall be held guilty of any criminal offence on account of any act or omission that did not constitute a criminal offence, under national or international law, at the time when it was committed. Nor shall a heavier penalty be imposed than the one that was applicable at the time when the criminal offence was committed. If, subsequent to the commission of the offence, provision is made by law for the imposition of the lighter penalty, the offender shall benefit thereby. 2. Nothing in this article shall prejudice the trial and punishment of any person for any act or omission which, at the time when it was committed, was criminal according to the general principles of law recognized by the community of nations. Article 7, ECHR: 1. No one shall be held guilty of any criminal offence on account of any act or omission that did not constitute a criminal offence under national or international law at the time when it was committed. Nor shall a heavier penalty be imposed than the one that was applicable at the time the criminal offence was committed. 2. This article shall not prejudice the trial and punishment of any person for any act or omission which, at the time when it was committed, was criminal according to the general principles of law recognised by civilised nations. A key aspect of the principle of legality is the outlawing of retroactive criminal laws and penalties. Such absolute protection is found in all the major human rights treaties (see box above). Therefore, in a number of cases the Human Rights Committee has found a violation of the prohibition of retroactive criminal law where people were convicted and sentenced for membership of subversive organizations that were legal political parties but which were subsequently banned.135 Importantly from a counter-terrorism perspective, this prohibition in international human rights law applies only to criminal proceedings resulting in a conviction, or the imposition of a criminal penalty. While other human rights standards will apply, the prohibition on retroactivity does not apply to internment or other forms of preventive detention that do not depend upon a criminal conviction or sentence. The prohibition does not generally apply to civil proceedings, although the definition of what is “criminal” is an autonomous concept. What is meant by an autonomous concept in international human rights law will be explained below. 135 HRC, Weinberger Weisz v. Uruguay, Communication No. 28/1978, doc. CCPR/C/11/D/28/1978, 29 October 1980, para 16. 64 Countering Terrorism, Protecting Human Rights