Exceptional circumstances can warrant exceptional measures, but also require exceptional justification, for example by means of a juridical decision for the individual case (i.e., a judge issuing a warrant allowing the police to install and use a backdoor on a concrete individual).
Let’s just remind that “exceptional justifications” in Canada were “Truckers are protesting with honks in the middle of cities”, so not exactly a matter of national security and in the USA, NSA took it to mean “Any US or non-US citizen on US or non-US soil” (for national security letters).
