Interjurisdictional immunity

[93] The doctrine of interjurisdictional immunity protects the “core” of a legislative head of power from impairment by the actions of a government at the other level: COPA, at para. 26. Its application involves two steps: (1) determining whether a statute or measure adopted by a government at one level trenches on the core of a power of the other government, and (2) determining whether the effect of the statute or measure on the protected power is sufficiently serious to trigger the application of the doctrine: COPA, at para 27.

[94] Its application has wide-ranging consequences and as the Supreme Court recently reiterated, it should be applied “with restraint” and “in general be reserved for situations already covered by precedent”: Bank of Montreal v. Marcotte, 2014 SCC 55, (2014) 2 S.C.R. 725, at para. 63, citing Canadian Western Bank, at paras. 67 and 77.

[95] I agree with the City’s submission that Canada Post has not identified any precedent recommending the application of this doctrine. It is not sufficient that the doctrine has in the past been applied to the head of power of postal services. There needs to be a closer nexus with the actual subject matter of the By-Law.

[96] As this case presents a novel situation with respect to interjurisdictional immunity, the application judge needed to identify some exceptional rationale for extending the doctrine and did not do so. Accordingly, I am of the view that the application of the doctrine in this instance is an error of law.