Sometimes failure to use lawful means would aggravate the wrongfulness. Other times the lawful alternative would diminish the wrongfulness. When?
The Supreme Court of Canada got to grips with this in R v Côté 2011 SCC 46 (14 October 2011). The context for this sort of decision in Canada is R v Grant 2009 SCC 32, which I had some fun with here on 18 July 2009 for its complex model of how admissibility of improperly obtained evidence is to be decided. Grant was referred to recently by the Supreme Court of New Zealand in Hamed v R, discussed here on 19 September 2011.
So to the vital bit of Côté. The term "discoverability" means the ability to discover the evidence lawfully. Two "branches" of the Grant model have to be addressed: the seriousness of the misconduct, and its impact on the defendant Cromwell J delivering the joint judgment):
I still think the Canadian model in Grant is absurdly complex: who can visualise a 3-branch balancing exercise? The third branch is the public interest in admission of the evidence. It would be better to think of the first two as being one "branch", or arm of the balance, with a weight moving one way or the other along it according to the first two considerations.
In Grant the model was called a "decision tree". Draw it for us. I had a go, but couldn't say it would make comparison of cases easy.