Limitations - Generally. Carmichael v. GlaxoSmithKline Inc.
In Carmichael v. GlaxoSmithKline Inc. (Ont CA, 2020) the Court of Appeal considered the general purposes of limitation periods:
 Traditionally, limitation periods were seen as having three purposes, known as the certainty, evidentiary, and diligence rationales: Novak v. Bond, 1999 CanLII 685 (SCC),  1 S.C.R. 808, at paras. 64-67; Canadian Imperial Bank of Commerce v. Green, 2015 SCC 60,  3 S.C.R. 801, at para. 57; and Frohlick v. Pinkerton Canada Limited, 2008 ONCA 3, 88 O.R. (3d) 401, at para. 18. The certainty rationale seeks “to promote accuracy and certainty in the adjudication of claims”; the evidentiary rationale seeks “to provide fairness to persons who might be required to defend against claims based on stale evidence”; and the diligence rationale seeks “to prompt persons who might wish to commence claims to be diligent in pursuing them in a timely fashion”: Green, at para. 57, citing Paul M. Perell and John W. Morden, The Law of Civil Procedure in Ontario, 2nd ed. (Markham: LexisNexis, 2014), at p. 123. In Novak, McLachlin J. (as she then was) observed that the three traditional rationales for limitation periods generally reflect the interests of potential defendants, based on the idea that they should not have to respond to stale claims brought by persons who have not asserted their rights diligently: at para. 64. But as legislatures have modernized their limitations statutes, they have increasingly focussed on the need to treat plaintiffs fairly and to account for their interests as well: at paras. 65-66. Today, therefore, a limitations statute “must attempt to balance the interests of both sides”: Murphy v. Welsh, 1993 CanLII 59 (SCC),  2 S.C.R. 1069, at p. 1080; see also Frohlick, at para. 19; Joseph v. Paramount Canada’s Wonderland, 2008 ONCA 469, 90 O.R. (3d) 401, at para. 8.. Canadian Imperial Bank of Commerce v. Green
In Canadian Imperial Bank of Commerce v. Green (SCC, 2015) the Supreme Court of Canada considered basic principles underpinning the existence of limitation periods:
 This Court has generally recognized that limitation periods have three purposes known as the certainty, evidentiary and diligence rationales: Novak v. Bond, 1999 CanLII 685 (SCC),  1 S.C.R. 808, at paras. 64-67, per McLachlin J.; M. (K.) v. M. (H.), 1992 CanLII 31 (SCC),  3 S.C.R. 6, at pp. 29-31, per La Forest J. Limitation periods serve “(1) to promote accuracy and certainty in the adjudication of claims; (2) to provide fairness to persons who might be required to defend against claims based on stale evidence; and (3) to prompt persons who might wish to commence claims to be diligent in pursuing them in a timely fashion”: P. M. Perell and J. W. Morden, The Law of Civil Procedure in Ontario (2nd ed. 2014), at p. 123.
 Clearly, it is desirable that litigation be accurate and certain, given that the passage of time dims memories and erodes evidence, and also that the risk of error grows as an adjudicator is further removed from the cause of action. Furthermore, after a certain time, possible defendants may be unaware of the need to preserve potentially enlightening or even exonerating pieces of evidence. Finally, it is appropriate to expect plaintiffs to assert their claims diligently and to be cognizant of their circumstances and of the extent of their control over them. Modern limitations legislation is therefore based on a recognition that limitation periods, in order to be effective, need to be final. This is the other side of the coin, the practical consequence of limitation periods that can make the application of a limitations statute seem harsh: Novak, at para. 8, per Iacobucci and Major JJ, dissenting.