1100997 Ontario Limited v. North Elgin Centre Inc., 2016 ONCA 848:
 A cause of action is "a factual situation the existence of which entitles one person to obtain from the court a remedy against another person": Letang v. Cooper,  1 Q.B. 232 (C.A.), at pp. 242-43, as adopted by this court in July v. Neal (1986), 57 O.R. (2d) 129 (C.A.), at para. 23.
 In Morden & Perell, The Law of Civil Procedure in Ontario, 2nd ed. (Markham: LexisNexis Canada Inc., 2014), at p. 142, the authors state:
A new cause of action is not asserted if the amendment pleads an alternative claim for relief out of the same facts previously pleaded and no new facts are relied upon, or amount simply to different legal conclusions drawn from the same set of facts, or simply provide particulars of an allegation already pled or additional facts upon which the original right of action is based. [Footnotes omitted.]
 In Dee Ferraro Ltd. v. Pellizzari, this court noted the distinction between pleading a new cause of action and pleading a new or alternative remedy based on the same facts originally pleaded. The appellants had commenced an action against their lawyer claiming damages for breaches of contract, trust and fiduciary duty and for fraud and negligence. The appellants then sought to amend their pleading. This court, in overturning the motion judge's dismissal of the motion to amend, concluded that the proposed amendments, such as claims for a mandatory order and a constructive trust over shares, could be made because they flowed directly from facts previously pleaded.
 By contrast, a proposed amendment will not be permitted where it advances a "fundamentally different claim" after the expiry of a limitation period: Frohlick v. Pinkerton Canada Ltd. In that case, the court did not permit the plaintiff in a wrongful dismissal action to amend the statement of claim to assert a claim for damages for constructive dismissal on the basis that the limitation period had expired. This court dismissed the appeal. The amendment regarding constructive dismissal related to events that occurred prior to the events described in the original statement of claim that were unrelated to that claim. The defendant was unaware of the new allegations prior to the plaintiff seeking the amendments, and the events were not put in issue or encompassed within the original claim.
 Based on the foregoing, an amendment will be refused when it seeks to advance, after the expiry of a limitation period, a "fundamentally different claim" based on facts not originally pleaded.
Of the Law Societies of Upper Canada and Nunavut