To boil it down, Peter proposes that when the Supreme Court of Canada rules that the "national security letters" are unconstitutional (which they blatantly are), Harper will call an election saying that security trumps all. This will allow the Conservatives, if re-elected, to use the notwithstanding clause (Sec. 33) and re-authorize the national security letters.
A note to my foreign readers: The Canadian constitution, in a fit of schizophrenia, allows the Federal or Provincial governments to effectively declare that the Charter of Rights and Freedoms (our Bill of Rights) doesn't apply to certain legislation. There is a time limit for each declaration - a law can only be charter-proof for five years at a time - but Sec. 33 can be re-used, in theory for ever.
Effectively, the Canadian charter of rights applies until the government doesn't say it doesn't, if you follow.
There are two historical interpretations for why Canada opted for this when, to my knowledge, no other liberal democracy has a similar clause to their constitution. The charitable interpretation is that while Trudeau and the Premiers wanted a guaranteed charter of rights, they also wanted to respect the principle of Parliamentary supremacy we inherited from the British.
The less-charitable (and in my mind, more accurate) interpretation is simply that the various governments (Provincial and Federal) were deathly afraid of their laws actually being held to any kind of standard, much less a constitutional one. Remember that in the context of the early 1980s, the two big movements were feminism and a nascent gay rights movement. The idea that the government would - horrors! - have to take gender (and racial, and economic, etc...) equality seriously scared more than a few politicians, who demanded an escape hatch.
The latest use of Sec. 33 was by Premier Klein, regarding (you guessed it!) gay marriage. Fortunately, the Court ruled that the law was beyond Alberta's jurisdiction, so it was null and void anyway.
To get back to the election idea of Peter's, it seems that nutball Conservatives like Preston Manning and Mike Harris are advocating that the current government "rehabilitate" the notwithstanding clause. Manning, in a ridiculous speech said
"We remind those who feel that the notwithstanding clause has no place in our Constitution that its inclusion was a condition of provincial acceptance of the Charter of Rights and Freedoms, and that indeed the Charter itself would not exist in law had the notwithstanding clause not been a part of it."Shorter Preston Manning: "We put a gun to your head, and like a sucker you gave in. Now we own you, bitch!"
What's really sad is that I have it on good authority - from people who should know - that Mike Harris hated Sec. 33 back when he was Premier of Ontario. Harris believed, and I'm paraphrasing, that you're either in the Constitution or not, and if you find that a law is unconstitutional then you change the law. To see him put his name to this piece of garbage is disappointing. On the plus side, Harris' stand on Sec. 33 was officially the last thing that gave me any respect for the man, so I can now say that Harris is officially the most worthless premier of Ontario ever.