I just have a comment rather than a question, but then you can comment on my comment if you so wish because I may not be right.
The security certificates as a device go back a long time, several decades in Canada. If I understood it correctly, they were brought in to deal with organized crime that may have roots elsewhere and have branches here, in the form of aliens or immigrants, permanent residents or visitors. So when you had to deal with people who were engaged in espionage or terrorism, at least for those of us who were not citizens, the tool came in handy because it was being used for criminal activity.
Although I understand all the concerns you have, because I come from that part of the world in terms of human rights, I don't think it's true to say that it's now being used. I think it's been used for deporting criminals who you otherwise couldn't prosecute because you didn't have the evidence here, the evidence was somewhere else, and the evidence may not be produceable in a way that would prove the crime beyond a reasonable doubt. So you took the liberty, because these were permanent residents and visitors--less than citizens--of saying, you're undesirables and we want to keep you out.
It has been extended currently to use in the case of those who we might fear might do damage to us. It's not that it is the most ideal tool, but there has been a regime for decades to deal with inadmissible permanent residents or visitors, so that even if you were less than a terrorist and you were simply a convicted rapist or somebody, you're deportable based on the decisions made by the Immigration Appeal Board, without having to prove beyond a reasonable doubt that you should be deported, that you would always be a threat to society.
Many of the presenters have raised this issue to say that because it is slightly a different system from the criminal law system, it is less justified. I may agree with you, but what do you have to say about that?