in right of Canada and of any province, but provincial statutes do not of their own force bind the federal Crown. There is considerable debate as to whether interprovincial sovereign immunity exists. In Re Upper Churchill Water Rights Reversion Act, an Act of the Newfoundland legislature was held to be unconstitutional because of colourability. While its stated purpose was to cancel a long-term lease and to expropriate power generation assets located in the province, its real purpose was to interfere with civil rights existing outside the province. As noted by Mr Justice McIntyre: Certain measures that would be constitutionally valid if enacted on their own are invalid if they are combined with other measures that invade unconstitutionally into the other jurisdiction. This is held to be overreach. As noted by Viscount Haldane: In Reference re Assisted Human Reproduction Act, the federal use of the criminal law power was found in certain key aspects to overreach too far into the provincial hospitals power, as well as into the more familiar sphere of property and civil rights. In Reference re Securities Act, a proposed federal law for establishing a national securities regulator was held to overreach, as a whole, too far into the property and civil rights power, and was thus wholly unconstitutional. "Double aspect" under Multiple Access Multiple Access Ltd v McCutcheon held that, even when federal and provincial laws have been enacted on the same matter by virtue of the double aspect doctrine, the doctrine of paramountcy does not necessarily have to be invoked. In that regard, Mr Justice Dickson observed: Therefore, paramountcy should only be invoked where there is a conflict between the federal and provincial laws in question. There is no danger of double recovery being possible where the laws are not in conflict, as no court would permit it. Canadian Western Bank principles The current approach to determining the constitutionality of legislation is founded in Canadian Western Bank v Alberta, where the Supreme Court of Canada summarized the following principles: the pith and substance of the provincial law and the federal law should be examined to ensure that they are both validly enacted laws and to determine the nature of the overlap, if any, between them. the applicability of the provincial law to the federal undertaking or matter in question must be resolved with reference to the doctrine of interjurisdictional immunity. only if both the provincial law