Under the current system, the minister's delegate, who is a CBSA hearings officer, makes representations and argues on a case-by-case basis whether detention should be continued because the identity hasn't been confirmed, whether there is concern about danger to the public, or whether there is a reason to believe that the individual might be inadmissible for criminality or security. That case is made to the quasi-judicial Immigration and Refugee Board. It makes the decision whether or not to maintain detention.
On April 30th, 2012. See this statement in context.