If an individual fears being returned to his country, the big question is why! What is it that the other counrty has on this person that makes him/her fear persecution if they are returned and why don't we want them anymore?
How many times do we have to hear that a person in question was free on bail when they committed another crime. Or that they've been deported several times and keep sneaking back in.
If it looks like a duck, walks like a duck and quacks like a duck, let's have a real close look.
This is not like the witch hunts where all you had to do was point the finger. There is an investgation, evidence is gathered and decissions are made. The days of "better 10 guilty go free than one innocent be condemned" are over!

Citizenship and Immigration Canada can remove a person considered to be a security threat by issuing a Security Certificate signed by the solicitor general and the minister of citizenship and immigration, and endorsed by a judge of the Federal Court(this is not just some cop making unjustified arrests).

When a security certificate is issued:
all other immigration proceedings are suspended until the Federal Court makes a final decision about the certificate(case is brought befor a court);
foreign nationals who are the subject of a Security Certificate are automatically detained(or do we just give them bail and watch while they disappear). Permanent residents may be detained on a case-by-case basis(MAY BE!).
If the Federal Court decides that the certificate is unreasonable, it is quashed(that's pretty simple). If the court decides that it is reasonable, the certificate becomes an order for removal of the person. The court's decision can't be appealed. Somebody, somewhere has to have a final say!