CRC/C/GC/24 imprisonment for offences committed by persons who were under the age of 18 at the time of commission of the offence. Monitoring the execution of measures, including placements 93. Specialized services such as probation, counselling or supervision should be established together with specialized facilities including for example non-residential community centres. Where necessary, facilities for residential care and treatment of child offenders may be established. Effective coordination, monitoring and quality control of the activities of all these specialized units, services and facilities should be promoted in an ongoing manner. Monitoring and evaluation of all measures must be included. In particular in case of placement or of detention, States parties have to plan the conditions of implementation, in accordance with paragraphs xx-xx above. 94. In addition, States parties have to conduct regular evaluations of their practice of juvenile justice, in particular of the effectiveness of, and compliance with, the measures taken, including those concerning discrimination, reintegration and recidivism, preferably carried out by independent academic institutions. Research, as for example on the disparities in the administration of juvenile justice which may amount to discrimination, and developments in the field of juvenile justice, such as effective diversion programmes or newly emerging juvenile justice strategies, will indicate critical points of success and concern. F. Deprivation of liberty, including pre-trial detention and post-trial incarceration 95. Article 37 of CRC contains the leading principles for the use of deprivation of liberty, the procedural rights of every child deprived of liberty, and provisions concerning the treatment of and conditions for children deprived of their liberty. Basic principles 96. The leading principles for the use of deprivation of liberty are: (a) the arrest, detention or imprisonment of a child shall be in conformity with the law and shall be used only as a measure of last resort and for the shortest appropriate period of time; and (b) no child shall be deprived of his/her liberty unlawfully or arbitrarily. 97. The Committee notes with concern that, in many countries, children languish in pretrial detention for months or even years, which constitutes a grave violation of article 37 (b) of CRC. An effective wide range of diversion options to avoid criminal justice proceedings should be available (see sections B and D above), for the States parties to realize their obligation under article 37 (b) of CRC to use deprivation of liberty only as a measure of last resort. The use of non-custodial measures must be carefully structured to reduce the use of pre-trial detention as well. In addition, even when children are to be tried in the juvenile justice system the States parties should take adequate legislative and other measures to reduce the use of pre-trial detention. 98. Use of pre-trial detention as a punishment violates the presumption of innocence. The law should clearly state the conditions that are required to determine whether to place or keep a child in pre-trial detention, in particular to ensure his/her appearance at the court proceedings, and whether he/she is an immediate danger to himself/herself or others. The duration of pre-trial detention should be limited by law and be subject to regular review. 99. In application of the principle of the shortest period of time, States parties should provide regular opportunities in their specialized juvenile justice system to permit early release from custody, including police custody, into the care of parents or other suitable adults. There should be a discretion to release with or without conditions, such as reporting to a police station or probation officer, and the payment of monetary bail should generally not be a requirement. Decisions regarding pre-trial detention, including its duration, should be accorded urgency and should be made as soon as possible by a competent, independent 18