beyond that age, when appropriate, the young age of perpetrators should be a factor in determining appropriate penalties.268 3.9 Human Rights and Rule of Law Imperatives for Effective Responses to Potential Threats and Challenges of FTFs Recommendations OSCE participating States should: • Adopt a human rights and rule of law-based approach in all measures aimed at countering the threats and challenges posed by FTFs, in recognition of the fact that security cannot be achieved at the expense of human rights and the rule of law; • Regularly review and carefully assess the implementation of FTF-related laws, policies and practices, including for their human rights impact, to ensure that all those measures are justified, necessary and proportionate, evidence-based and targeted; and • Acknowledge past shortcomings and provide for effective remedies and, where necessary, reparation to individuals whose rights have been infringed upon, in order to ensure the credibility and legitimacy on which the effectiveness of FTF-related measures depends. If efforts to counter the potential threats posed by FTFs, including related measures to prevent and counter VERLT, are to be effective and not based on flawed assumptions, it is essential that states continue to develop their understanding of the manifestations of FTF-activity. Otherwise, efforts could be based on flawed assumptions. This is particularly important in light of constantly changing facts, trends and challenges in relation to FTFs. While the success of counter-terrorism efforts, and of VERLT-prevention programmes, is inevitably difficult to demonstrate, ongoing analysis and regular review is essential to evaluate effectiveness, address potential negative effects on human rights, and to convincingly demonstrate the necessity and proportionality of those measures. In addition to periodic reviews, the UN CTITF Guidance to states recommends that legal provisions establishing special powers to address particular terrorist threats should be subject to sunset clauses, which require the renewal of the provisions after a specific time. These would help to ensure that such powers do not remain in force when no longer necessary.269 268  While the UN Committee on the Rights of the Child stressed that, in accordance with Article 40 CRC, every child under 18 years must be treated in accordance with the rules of juvenile justice, it noted with appreciation good practice in some States that apply the rules and regulations of juvenile justice to persons aged 18 and older, usually until the age of 21. See: General Comment No. 10, UN Committee on the Rights of the Child, paras. 37-38, op. cit., note 263. 269  UN CTITF Guidance 2018, op. cit., note 10, p. 44-45. The recommendation was made by the UN Special Rapporteur on counter-terrorism, UN. Doc A/HRC/16/51 (“Ten areas of best practice in countering terrorism”), Practice 4 (1), paras. 17-20 op. cit., note 73. Guidelines for Addressing the Threats and Challenges of “Foreign Terrorist Fighters” 73