Penner v. Niagara (Regional Police Services Board) 2013 SCC 19 deals with issue estoppel.
The legal framework governing the exercise of the discretion not to apply issue estoppel is set out in Danyluk v. Ainsworth Technologies, 2001 SCC 44,  2 S.C.R. 460. This framework has not been overtaken by the Court's subsequent jurisprudence.
While finality is important both to the parties and to the judicial system, unfairness in applying issue estoppel may nonetheless arise.
First, the prior proceedings may have been unfair.
Second, even where the prior proceedings were conducted fairly, it may be unfair to use the results of that process to preclude the subsequent claim, for example, where there is a significant difference between the purposes, processes or stakes involved in the two proceedings. The text and purpose of the legislative scheme shape the parties' reasonable expectations in relation to the scope and effect of the administrative proceedings. They guide how and to what extent the parties participate in the process. Where the legislative scheme contemplates multiple proceedings and the purposes of those proceedings are widely divergent, the application of the doctrine might not only upset the parties' legitimate and reasonable expectations but may also undermine the efficacy and policy goals of the administrative proceedings, by either encouraging more formality and protraction or discouraging access to the administrative proceedings altogether. These considerations are also relevant to weighing the procedural safeguards available to the parties.
A decision whether to take advantage of those procedural protections available in the prior proceeding cannot be divorced from the party's reasonable expectations about what is at stake in those proceedings or the fundamentally different purposes between them. The connections between the relevant considerations must be viewed as a whole.
The Court holds:
 Issue estoppel, with its residual discretion, applies to administrative tribunal decisions. The legal framework governing the exercise of this discretion is set out in Danyluk. In our view, this framework has not been overtaken by this Court's subsequent jurisprudence. The discretion requires the courts to take into account the range and diversity of structures, mandates and procedures of administrative decision makers however, the discretion must not be exercised so as to, in effect, sanction collateral attack, or to undermine the integrity of the administrative scheme. As highlighted in this Court's jurisprudence, particularly since Dunsmuir v. New Brunswick, 2008 SCC 9,  1 S.C.R. 190, legislation establishing administrative tribunals reflects the policy choices of the legislators and administrative decision making must be treated with respect by the courts. However, as this Court said inDanyluk, at para. 67: "The objective is to ensure that the operation of issue estoppel promotes the orderly administration of justice but not at the cost of real injustice in the particular case."
 This Court in Danyluk, at paras. 68-80, recognized several factors identified by Laskin J.A. in Minott v. O'Shanter Development Co. (1999), 42 O.R. (3d) 321 (C.A.), that are relevant to the discretionary analysis in the context of a prior administrative tribunal proceeding.
 The list of factors in Danyluk merely indicates some circumstances that may be relevant in a particular case to determine whether, on the whole, it is fair to apply issue estoppel. The list is not exhaustive. It is neither a checklist nor an invitation to engage in a mechanical analysis.
 Broadly speaking, the factors identified in the jurisprudence illustrate that unfairness may arise in two main ways which overlap and are not mutually exclusive. First, the unfairness of applying issue estoppel may arise from the unfairness of the prior proceedings. Second, even where the prior proceedings were conducted fairly and properly having regard to their purposes, it may nonetheless be unfair to use the results of that process to preclude the subsequent claim.