The crucial importance of the distinction between prosecutorial discretion reviewable only for abuse of process and matters of tactics or conduct before the court governed by the inherent jurisdiction of the criminal trial court to control its own process was fully canvassed and explained inKrieger v. Law Society of Alberta, 2002 SCC 65 (CanLII), 2002 SCC 65,  3 S.C.R. 372.
Subject to the abuse of process doctrine, supervising one litigant’s decision-making process — rather than the conduct of litigants before the court — is beyond the legitimate reach of the court. The Crown’s decision in this case to resile from the plea agreement and to continue the prosecution clearly constituted an act of prosecutorial discretion subject to the principles set out in Krieger: it is only reviewable for abuse of process. Prosecutorial discretion is not spent with the decision to initiate the proceedings, nor does it terminate with a plea agreement. So long as the proceedings are ongoing, the Crown may be required to make further decisions about whether the prosecution should be continued, and if so, in respect of what charges.
There are two categories of abuse of process under s. 7 of the Charter: (1) prosecutorial conduct affecting the fairness of the trial; and (2) prosecutorial conduct that contravenes fundamental notions of justice and thus undermines the integrity of the judicial process. While s. 24(1) of theCharter allows for a wide range of remedies, this does not mean that abuse of process can be made out by demonstrating a lesser degree of harm, either to the accused’s fair trial interests or to the integrity of the justice system. Achieving the appropriate balance between societal and individual concerns defines the essential character of abuse of process.
The repudiation of a plea agreement may well constitute an abuse of process, either because it results in trial unfairness or meets the narrow residual category of abuse that undermines the integrity of the judicial process. The more difficult question in this appeal is how the initial exercise of prosecutorial discretion — Crown counsel’s offer to resolve the matter on the basis of a plea to a lesser charge — should figure in the analysis regarding abuse of process.
A plea agreement should not be regarded as a contractual undertaking. Vitiating factors, such as mistake, misrepresentation or fraud, which usually inform a private party’s right to resile from a bargain, do not fully capture the public interest considerations which are at play.
However, the analogy can usefully underscore the utmost importance of honouring the agreement. The situations in which the Crown can properly repudiate a plea agreement are, and must remain, very rare. Moreover, the reasonably defensible test applied by the application judge to Crown counsel’s decision to enter into a plea agreement is not the appropriate measure to determine whether there is an abuse of process. Indeed, it is the circumstances surrounding the repudiation of a plea agreement which should be reviewed to determine whether that decision amounts to an abuse of process. Reviewing for “reasonableness” a decision made in the exercise of prosecutorial discretion runs contrary to the constitutionally separate role of the Attorney General in the initiation and pursuit of criminal prosecutions as well as the principles set out in Krieger.
Given that acts of prosecutorial discretion are generally beyond the reach of the court, there is good reason to impose a threshold burden on the applicant who alleges abuse of process. A court should not embark on an inquiry into the reasons behind the exercise of prosecutorial discretion without a proper evidentiary foundation.
However, evidence that a plea agreement has been entered into and subsequently reneged by the Crown meets the requisite threshold. Further, to the extent that the Crown is the only party who is privy to the information, the evidentiary burden shifts to the Crown to enlighten the court on the circumstances and reasons behind its decision to resile from the agreement. The ultimate burden of proving abuse of process, however, remains on the applicant.
In this case, the Crown’s repudiation conduct cannot be considered so unfair or oppressive to the accused, or so tainted by bad faith or improper motive, that to allow the Crown to now proceed on the dangerous driving Criminal Code charges would tarnish the integrity of the judicial system and thus constitute an abuse of process. Indeed, the Acting Assistant Deputy Minister, in good faith, determined that Crown counsel’s assessment of the strength of the evidence was erroneous and, on that basis, having regard to the seriousness of the offences, concluded that it would not be in the public interest to terminate the prosecution on the criminal charges. This can hardly be regarded as evidence of misconduct. Finally, the accused was returned to the position she was in at the conclusion of the preliminary hearing before the plea agreement was entered into and thus suffered no prejudice as a result of the repudiation.
Source: R. v. Nixon, 2011 SCC 34.