Abuse of Process - In Relation to Other Doctrine. Flores v. Glegg
In Flores v. Glegg (Ont CA, 2022) the Court of Appeal pronounced on the breadth of the abuse of process doctrine:
 One of the objectives of abuse of process is to protect the integrity of the court’s process by preventing a party from relitigating matters that have already been finally determined. As the Supreme Court of Canada held in Toronto (City) v. C.U.P.E., Local 79, 2003 SCC 63,  3 SCR 77, at paras. 35-55, the doctrine is related to the common law doctrines of res judicata, issue estoppel and collateral attack, but is more flexible because it is available even where, as in this case, one or more parties to the action were not parties to the underlying action. The doctrine of abuse of process also applies to prevent re-litigation of previously decided facts, namely, whether O.G. was brainwashed by her mother: Winter v Sherman Estate, 2018 ONCA 703, at para. 8.. Kirsh v. Bristol-Myers Squibb
In Kirsh v. Bristol-Myers Squibb (Div Ct, 2021) the Divisional Court considered the doctrine of abuse of process:
 The doctrine of abuse of process is meant to be more flexible than the doctrines of res judicata or issue estoppel. The court can stay an action as an abuse of process to prevent a party from relitigating an issue already decided or from bringing duplicative proceedings.The case also considered abuse of process in the context of overlapping class actions [paras 41-57].
 As held by the Supreme Court of Canada in Behn v. Moulton Contracting Ltd., 2013 SCC 26, at para. 40, the “doctrine of abuse of process is characterized by its flexibility”. It gives courts the inherent power to prevent the misuse of the court’s procedures “in a way that would be manifestly unfair to a party to the litigation before it or would in some other way bring the administration of justice into disrepute”. At para. 41 of Moulton Contracting, the Court stated that “the administration of justice and fairness are at the heart of the doctrine of abuse of process” and, at para. 42 that the “doctrine of abuse of process is flexible, and it exists to ensure that the administration of justice is not brought into disrepute”.
. Floria v. Toronto Police Service
In Floria v. Toronto Police Service (Div Ct, 2021) the Divisional Court considered the role of excess delay in an administrative context as a form of abuse of process:
 The Supreme Court held in Blencoe v. British Columbia (Human Rights Commission), 2000 SCC 44 that an inordinate delay in an administrative proceeding may amount to an abuse of process, such that the proceeding should be stayed (at para. 121). However, the Court emphasized that a lengthy or inordinate delay alone is not sufficient. Rather, the delay must result in significant prejudice to the party seeking a remedy. He or she must show significant prejudice to the fairness of the hearing, impairing the ability to defend (at para. 102). Alternatively, the party must show that the delay has caused significant psychological or reputational harm. At para. 115, the majority stated:. Apotex Inc. v. Schering Corporation
The doctrine of abuse of process is not limited to acts giving rise to an unfair hearing; there may be cases of abuse of process for other than evidentiary reasons brought about by delay. It must however be emphasized that few lengthy delays will meet this threshold. I caution that in cases where there is no prejudice to hearing fairness, the delay must be clearly unacceptable and have directly caused a significant prejudice to amount to an abuse of process. It must be a delay that would, in the circumstances of the case, bring the human rights system into disrepute. The Court also emphasized that the determination of inordinate delay is contextual, stating at para. 122:
The determination of whether a delay has become inordinate depends on the nature of the case and its complexity, the facts and issues, the purpose and nature of the proceedings, whether the respondent contributed to the delay or waived the delay, and other circumstances of the case. As previously mentioned, the determination of whether a delay is inordinate is not based on the length of the delay alone, but on contextual factors, including the nature of the various rights at stake in the proceedings, in the attempt to determine whether the community’s sense of fairness would be offended by the delay. I agree with the Commission’s conclusion upholding the Hearing Officer’s ruling on abuse of process. The Hearing Officer carefully examined the length of the delay and the reasons for it, as the Commission observed. However, I note that the Commission seems to focus only on the analysis of the length of the delay by the Hearing Officer (at paras. 31-33).
 In administrative law, the length of the delay is not the only consideration in determining whether there has been an abuse of process. The tribunal must also consider the prejudice from the delay to determine whether the continuation of the proceeding is an abuse of process. While the Commission recognized the need for evidence of real and significant prejudice arising from the delay when it set out the test in Blencoe (Reasons, para. 27), it fails to examine this aspect of the test when it considers the Hearing Officer’s reasons, focusing on her analysis of the delay.
In Apotex Inc. v. Schering Corporation (Ont CA, 2018) the Court of Appeal applies it's discretion not to apply the equitable doctrine of issue estoppel if it would do an injustice in the case, and in doing so identifies the doctrines of issue estoppel and collateral attack as sub-categories of the larger doctrine of abuse of process:
 I would note, at the outset, that the scope of the “special circumstances” exception to issue estoppel constitutes a question of law. The standard of review is thus one of correctness: Housen v. Nikolaisen, 2002 SCC 33 (CanLII),  2 S.C.R. 235, at para. 8.
 The requirements of, and purpose behind, the doctrine of res judicata were thoroughly canvassed in Danyluk v. Ainsworth Technologies Inc., 2001 SCC 44 (CanLII),  2 S.C.R. 460. In that decision, Binnie J. reviewed the historical development of the doctrine and its component parts: cause of action estoppel and issue estoppel. He also reviewed the development of the doctrine of collateral attack.
 As set out in Danyluk at para. 25, the preconditions to the operation of issue estoppel are: (i) that the same question has been decided; (ii) that the judicial decision which is said to create the estoppel was final; and, (iii) that the parties to the judicial decision or their privies were the same persons as the parties to the proceedings in which the estoppel is raised or their privies. It is clear that those three preconditions are met in this case.
 However, Binnie J. went on in Danyluk to point out that the court retained a discretion not to apply the doctrine where to do so would work an injustice. More specifically, Binnie J. adopted the observation in British Columbia (Minister of Forests) v. Bugbusters Pest Management Inc. (1998), 1998 CanLII 6467 (BC CA), 159 D.L.R. (4th) 50 (B.C.C.A.) where Finch J.A. said, at para. 32:
It must always be remembered that although the three requirements for issue estoppel must be satisfied before it can apply, the fact that they may be satisfied does not automatically give rise to its application. Issue estoppel is an equitable doctrine, and as can be seen from the cases, is closely related to abuse of process. The doctrine of issue estoppel is designed as an implement of justice, and a protection against injustice. It inevitably calls upon the exercise of a judicial discretion to achieve fairness according to the circumstances of each case. Binnie J. added, 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. Finally, Binnie J. concluded with a statement of what he said was the most important factor in deciding whether issue estoppel ought to be applied in any given case. He said, at para. 80:
As a final and most important factor, the Court should stand back and, taking into account the entirety of the circumstances, consider whether application of issue estoppel in the particular case would work an injustice. The exercise of the discretion to apply issue estoppel was also the subject of the decision of this court in Minott v. O'Shanter Development Co. (1999), 1999 CanLII 3686 (ON CA), 42 O.R. (3d) 321 (C.A.). Of particular importance, for the purposes of this case, is the observation of Laskin J.A. at para. 51 where he said:
If the decision of a court on a point of law in an earlier proceeding is shown to be wrong by a later judicial decision, issue estoppel will not prevent relitigating that issue in subsequent proceedings. It would be unfair to do otherwise.....
 For the reasons set out above, the appellants’ proposed amendments are also not barred by the doctrine of collateral attack. In Toronto (City) v. C.U.P.E., Local 79, 2003 SCC 63 (CanLII),  3 S.C.R. 77, the Supreme Court of Canada described issue estoppel and collateral attack as “particular applications of a broader doctrine of abuse of process” [italics added] (at para. 22). Though not entirely interchangeable, the Supreme Court went on to hold the following, at para. 53:
The discretionary factors that apply to prevent the doctrine of issue estoppel from operating in an unjust or unfair way are equally available to prevent the doctrine of abuse of process from achieving a similar undesirable result.As the application of collateral attack in this case would work the same injustice as issue estoppel, it should not be applied to block the proposed pleadings.