The cases holding otherwise are legion. Mr. Justice Riddel in Florence Mining put it thusly:
In short, the Legislature within its jurisdiction can do everything that is not naturally impossible, and is restrained by no rule human or divine. If it be that the plaintiffs acquired any rights, which I am far from finding, the Legislature had the power to take them away. The prohibition "Thou shall not steal," has no legal force upon the sovereign body. And there would be no necessity for compensation to be given.
The appellate courts, including the highest in the Empire, found nothing odd about these words. In British law, it was clear that the legislature could do what it wanted. In Canada, this was always restricted somewhat by the written constitution (which, as imperial legislation, was paramount over merely colonial statutes). But Dr. Bonham's case was roundly rejected.
But that was then.
Chief Justice of Canada Beverly McLachlin has told some New Zealand law students that she intends to imitate Lord Coke and strike down laws for violating unwritten principles.
The difficulty is not with the idea of unwritten principles. Surely, these exist. But someone must be final on the subject of what they mean, and how they apply to the issues of the day. In our system, that has always been the legislature.
McLachlin is willing to take the argument to the enemy, since she is in the current issue of whatever Western Report is now called. I would be less cynical about this development if it did not always seem to benefit lawyers in the crudest possible way.