Statutory Interpretation - Retrospectivity
R v Bengy (Ont CA, 2015)
In this case the Court of Appeal stated the law respecting the retrospective application of new legislation, in particular the distinction made on this issue between substantive and procedural rights, as follows:
What is the nature of the presumption against retrospectivity and what is its policy rationale?
 The leading and most recent authority on the presumption against retrospectivity is the Supreme Court decision in R. v. Dineley, 2012 SCC 58 (CanLII),  3 S.C.R. 272. In Dineley, the court was divided four to three over whether Parliament’s repeal of the “Carter defence” in the drinking and driving context was applicable to – and therefore removed the defence from – defendants who were tried post-amendment, but allegedly committed offences pre-amendment. The court was unanimous on the governing principle, expressed by the majority at para. 10 (and adopted by the dissent at paras. 45-47):
New legislation that affects substantive rights will be presumed to have only prospective effect unless it is possible to discern a clear legislative intent that it is to apply retrospectively…. However, new procedural legislation designed to govern only the manner in which rights are asserted or enforced does not affect the substance of those rights. Such legislation is presumed to apply immediately to both pending and future cases. Applying this principle, the court was divided over whether the amendment was properly characterized as affecting substantive or procedural rights. The majority concluded the amendment affected substantive rights and therefore applied strictly prospectively. Accordingly, the former Carter defence was available to those persons alleged to have committed offences prior to the amendment, even if their trials took place after the amendment. Conversely, the minority concluded the amendment was procedural and therefore retrospectively removed the defence from all persons tried after it came into force.
 Deschamps J., writing for the majority, at para. 10., explained the principle that animates the presumption against retrospectivity: “Because of the need for certainty as to the legal consequences that attach to past facts and conduct, courts have long recognized that the cases in which legislation has retrospective effect must be exceptional.”
 In Carriere, Wakeling J. referred to the policy rationale behind the presumption, at para. 57, as described in Sullivan on the Construction of Statutes, 5th ed. (Markham: LexisNexis, 2008):
Perhaps the most fundamental tenet of the rule of law is that those who are governed by the law must have knowledge of its rules before acting; otherwise, any compliance with the law on their part is purely accidental. Citizens must have knowledge of the law before acting so that they can adjust their conduct to avoid undesirable consequences and secure desirable ones. To ensure adequate notice, the rules enacted by the legislature must be published and adequately publicized – ideally before commencement but at the latest upon commencement.… Citizens cannot comply with, rely on or take advantage of law unless they know what it is before deciding how they will behave.