A/72/178 arbitrary executions that the United Nations High Commissioner for Human Rights convene an expert group to examine the application of the international human rights framework to “less lethal” weapons and unmanned systems for law enforcement purposes, including with a focus on their use in the context of assemblies. D. Monitoring, investigation, redress and rehabilitation 70. States should establish effective systems for monitoring and reporting on the use of force, and relevant information should be made accessible to the public, including statistics on when, against whom and through which means force is used and on the resulting harm. 71. For States parties to the Optional Protocol to the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, a key role in that respect could be assumed by national preventive mechanisms. Although the Optional Protocol does not require States to provide national preventive mechanisms with powers of oversight outside places where persons are deprived of their liberty, nothing in the relevant instruments prevents the extension of their monitoring responsibilities, as a matter of national law, to the use of force in extra-custodial settings. 73 72. States should systematically include the extra-custodial use of force in their regular reports to international mechanisms, such as the Committee against Torture and the Human Rights Committee (universal periodic review), and encourage international mechanisms, such as the Special Rapporteur on torture and other cruel, inhuman or degrading treatment or punishment and other special procedures, to examine the issue in their work. 73. Wherever there is reasonable ground to believe that extra-custodial force amounting to torture or other cruel, inhuman or degrading treatment or punishment has been used, States should conduct a prompt and impartial investigation in order to ensure full accountability for any such act, including, as appropriate, administrative, civil and criminal accountability, and to ensure that victims receive adequate redress and rehabilitation (General Assembly resolution 70/146, paras. 28-31). The Istanbul Protocol is a key resource on best practice in conducting such investigations. 74 __________________ 73 74 24/24 Examples of national preventive mechanisms monitoring the extra-custodial use of force are those of Austria (Austrian Ombudsman Board, “Annual report on the activities of the Austrian national preventive mechanism, 2014”, international version, June 2015, p. 2, and “Annual report, 2015”, international version, October 2016, pp. 208, 218 and 235, on police conduct during demonstrations and raids) and Brazil (2014 investigation into the use of force during a demonstration, available from http://apt.ch/en/blog/world-cup-preventing-torture-in-rio-dejaneiro/#.WU1CmpDyvIW). Manual on the Effective Investigation and Documentation of Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (Istanbul Protocol), Professional Training Series No. 8/Rev.1 (United Nations publication, Sales No. E.04.XIV.3). 17-12326