I am opposed to that for a number of reasons. First of all, the analog in the criminal law and in the charter jurisprudence, and even in the United States under the Bill of Rights, is that derivative evidence is not allowed, because then effectively you let police or security agencies or whatever they are break the law, since they know they can still get what they want indirectly. They'll torture you and they won't use the primary evidence, but they'll still get the fruits.
I think the U.S. coined the term, “fruits of the poisoned tree”. We don't take the fruits of the poisoned tree, because the source is wrong. If we want to discourage the use of torture to derive evidence, the best way to do that is really to say, if you play this game, none of it is getting in. You snuff it out right there.
I know there's been some academic dancing around this, with Mr. Dershowitz starting to make this a sexy topic—to talk about torture—but it doesn't work. He's fundamentally wrong as a lawyer I think because we all know that except in some rare circumstances, torture gives unreliable evidence—we've seen that in the Arar case—and it is fundamentally immoral; and third, it's impractical, because I think what we end up doing.... The whole torture debate in the United States, as we've seen in the war on terror, is that when we start to break the moral and legal rules of the world, we send the signal to others to start doing those things. I think that's why we need to draw the line.