A/HRC/20/19 are distinct, but complementary, and their proper performance is necessary to guarantee a fair, impartial and effective administration of justice. 38. In countries where the prosecution service is part of the judiciary, the careers of judges and prosecutors are usually governed by the same body, that is a Superior Council of Judiciary or a similar body. As noted earlier, in such cases, prosecutors and judges may have the possibility, albeit limited, to switch careers. 39. The opportunity to switch careers is considered useful by some prosecutors and judges since it enables them to obtain a broader perspective and understanding of both roles. However, the Special Rapporteur is of the opinion that this could potentially affect their independence and impartiality, or at least the appearance thereof, especially considering that they have different functions and play different roles, although both need to be highly qualified. Swapping roles may allow for the possibility of the same person becoming a judge in one’s own cause. In many countries, the careers of judges and prosecutors are separate and the possibility of switching between roles is subject to a competitive selection process. 40. Irrespective of the system applied, the role of prosecutors should not be confused with the role of judges. It is also important that prosecutors and judges be perceived by the general public as performing different roles and functions, as public confidence in the proper functioning of the rule of law is best ensured when every State institution respects each other’s sphere of competence.12 This is essential to uphold public confidence in the principle of equality of arms and the fair administration of justice. The role of prosecutors in relation to the police 41. The relationship between the police and prosecutors is essential to ensuring smooth criminal prosecutions. Within the different categories, a general divide can be made between the police service that carries out investigations independently of the prosecution service, and the police service that is subordinate to the prosecution service. 42. In States with an independent police force, prosecutors are not entitled to instruct the police, although the possibility exists whereby prosecutors, after receiving the case file, can request additional investigatory measures for the prosecution. In the case of subordination, the prosecution service can instruct the police to carry out investigations and to assess the legality of investigatory practices. Prosecutors also have the power to carry out investigations themselves, which requires training in investigatory and forensic skills. 43. In several States, the growing importance of security police forces has led to the allocation of more resources and powers to police services. While the strengthening of the police service should be generally welcomed, the Special Rapporteur is concerned that in certain cases the police may overpower the prosecution services. In this respect, the Special Rapporteur stresses that, especially where the police service is independent of the prosecution service, effective measures must be taken to guarantee that prosecutors and the police cooperate in an appropriate manner 13 in order to obtain the best and most fair outcome, especially for victims. She also highlights the need for prosecutors to bring impartial and objective judgement to bear on case files prepared by police or investigators. 12 13 See A/HRC/20/19/Add.3, para. 86. Council of Europe, Recommendation Rec (2000) 19 (see footnote 10 above), paras. 21 and 22. 9