Moot court cases occur when a determination is sought on a matter which when decided by the court will not have any practical effect on the existing dispute such as the legal issue no longer exists.
The courts do however have discretion when the moot case is important enough to hear the case such as occurred in DaGG V Cameron Estate 2017 ONCA 366 where there was a strong public issue that required determination.
The General Principles of Moot Court Cases
31 Where, as here, the dispute between the parties has disappeared, the court still retains the discretion to proceed to hear the merits of the appeal: Borowski v. Canada (Attorney General),  1 S.C.R. 342 (S.C.C.), at p. 353.
32 The exercise of that discretion is guided by a consideration of the presence or absence of the three rationales underpinning the mootness doctrine:
(i) whether the issues can be well and fully argued by parties who have a stake in the outcome;
(ii) the concern for judicial economy; and
(iii) the need for the court to remain alive to the proper limits of its law-making function in order to avoid intrusions into the role of the legislative branch: Borowski, at pp. 358-63; Ontario Provincial Police Commisioner v. Mosher, 2015 ONCA 722, 330 C.C.C. (3d) 149 (Ont. C.A.), at paras. 31-32. The interplay amongst the three rationales was described in Borowski at p. 363:
In exercising its discretion in an appeal which is moot, the Court should consider the extent to which each of the three basic rational for enforcement of the mootness doctrine is present. This is not to suggest that it is a mechanical process. The principles identified above may not all support the same conclusion. The presence of one or two of the factors may be overborne by the absence of the third, and vice versa.
Application of the principles in Moot Court Cases
33 Applying these criteria to this appeal, I have no concern about the absence of an adversarial relationship. Counsel for both parties argued the appeal with the same vigour as if the matter were not moot.
34 Regarding the factor of judicial economy, I am persuaded that although this is a case capable of repetition, it is one that could be evasive of review by this court given the costly three-stage appeal process involved: Borowski, at pp. 360, 364; Mosher, at para. 34
35 As well, there exists a strong public interest in the resolution of the legal issues raised by this appeal: Tamil Co-operative Homes Inc. v. Arulappah (2000), 49 O.R. (3d) 566 (Ont. C.A.), at paras. 25 and 26. The parties point to the long-standing practice in this province of including in separation agreements and court spousal and child support orders provisions requiring a payor spouse to maintain life insurance coverage and name the recipient spouse and children as beneficiaries under the policy. The effect of the Divisional Court’s decision is to expose such life insurance proceeds to competing claims under the SLRA from other children and former or subsequent spouses of the deceased payor. The implications of the Divisional Court decision will be felt well beyond the boundaries of this case.
36 Finally, the parties are not asking the court to decide an abstract question and thereby intrude improperly into the legislative sphere: Borowski, at p. 365. The issues raised by the parties are grounded in the specific facts in the record. The appeal was fully argued by interested parties based on a complete record, which puts the court in a position to make a fully informed decision on the issues of public importance raised by the appeals.
37 For these reasons, I would exercise our discretion to determine the issues raised in the appeal despite its mootness.