The Court holds:
 I begin with the procedural rights exception to the presumption against the retrospectivity of legislation. At common law, procedural legislation is presumed to apply immediately, to both pending and future facts. As Sullivan, supra, discusses at p. 696, this "presumption of immediate application" has been characterized, variously, in these terms: (1) there is no vested right in procedure; (2) the effect of a procedural change is deemed beneficial for all; (3) procedural provisions are an exception to the presumption against retrospectivity; and (4) procedural provisions are ordinarily intended to have an immediate effect. Sullivan also notes, at p. 696, the following early formulation of the rule in Wright v. Hale (1860), 6 H. & N. 227, at p. 232:
[W]here the enactment deals with procedure only, unless the contrary is expressed, the enactment applies to all actions, whether commenced before or after the passing of the Act.
 Canadian courts have recognized that the determination of whether a legislative provision is "purely" procedural requires examination of the substance of the provision and its practical impact on the parties. In Martin v. Perrie,  1 S.C.R. 41, at p. 48, the Supreme Court of Canada cited with approval Yew Bon Tew v. Kenderaan Bas Mara,  1 A.C. 533 (P.C.), at p. 562 for the principle that the substance of a provision, rather than the label assigned to it, is controlling of whether it is procedural in nature. The central question is whether the provision, if applied retrospectively, would impair existing rights and obligations. If so, the provision is not purely procedural and cannot be given retrospective effect.
 Martin also confirms that the intention of the legislature to interfere with vested rights and obligations must be express. The Supreme Court explained, at pp. 49 to 50, citing Spooner Oils Ltd. v. Turner Valley Gas Conservation,  S.C.R. 629, at p. 638:
A legislative enactment is not to be read as prejudicially affecting accrued rights, or "an existing status" ... unless the language in which it is expressed requires such a construction ... the underlying assumption being that, when Parliament intends prejudicially to affect such rights or such a status, it declares its intention expressly, unless, at all events, that intention is plainly manifested by unavoidable inference. [Citations omitted.]
 More recently, in Re s. 83.28, supra, the Supreme Court of Canada considered whether s. 83.28 of the Criminal Code (the Code), introduced as a result of the enactment of the Anti-terrorism Act, S.C. 2001, c. 41, applied retrospectively. Section 83.28 authorized the obtaining, on ex parte application, of an order for a judicial investigative hearing concerning suspected terrorism offences. The issue was whether s. 83.28 applied in circumstances where the terrorism offences at issue were committed before the Anti-terrorism Act came into force.
 In Re s. 83.28, the majority cautions, at para. 56, that an assessment whether a provision is or is not procedural must be determined in the circumstances of each case. Further, "for a provision to be regarded as procedural, it must be exclusively so" [citations omitted]. The majority concluded, at paras. 56 and 60 to 61, that s. 83.28 of the Code was purely procedural in nature since it merely provided: "a mechanism for the gathering of information and evidence in the ongoing investigation of past, present and future offences" and "outline[d] the process by which judicial investigative hearings are to be carried out."