The Attorney General certificate is a certificate signed by the Attorney General of Canada to prevent sensitive government information from being disclosed. Originally I believe it allowed for the duration of that certificate to be 15 years, but because a recommendation was made by one of the parliamentary committees reviewing the Anti-terrorism Act that this period of time be reduced from 15 years to 10 years, that recommendation appears in Bill S-7.
On November 19th, 2012. See this statement in context.