On the last question, the answer is that an average of 850 foreign nationals appeal a removal order based on inadmissibility for reasons of serious criminality. For example, in 2009, it was 1,086 people; last year it was 564. But on average it's 850. There are currently 2,747 appeals of inadmissibility on grounds of serious criminality pending before the Immigration Appeal Division.
On the earlier questions, about what would circumscribe the minister's discretion, frankly, his or her accountability to Parliament and to law would; the decisions cannot be made in a capricious manner.
The cases would be brought to the minister's attention, presumably in most cases by the Border Services Agency, but frankly, often these things arise in the media. Usually, when we're talking about some crazy hate-monger who is coming into Canada, I hear about it from members of a particular community who are concerned that this person is coming in. They will contact us through MPs or they'll make it known through the media.
The point I have made before is that there already is very broad discretion under IRPA in terms of positive discretion: it's the power of temporary resident permits—which, I point out, I have used much more sparingly than any of my predecessors, I think. Last year I think I issued fewer than 100 temporary resident permits under ministerial authority.
The negative discretion would be an analogous authority, in the sense that it would be broad but would be used with great discretion.