Crown Counsel owes an overarching duty to achieve justice by exercising their power fairly. The classic statement was set out by the Supreme Court of Canada in R v Boucher,  S.C.R. 16 at 23:
It cannot be over-emphasized that the purpose of a criminal prosecution is not to obtain a conviction; it is to lay before a jury what the Crown considers to be credible evidence relevant to what is alleged to be a crime. Counsel have a duty to see that all available legal proof of the facts is presented: it should be done firmly and pressed to its legitimate strength but it must also be done fairly. The role of the prosecutor excludes any notion of winning or losing; his function is a matter of public duty than which in civil life there can be none charged with greater personal responsibility. It is to be efficiently performed with an ingrained sense of the dignity, the seriousness and the justness of judicial proceedings.