I think there is a fair amount of common sense on the exemptions. Nobody thinks the public should be invited to CSIS security briefings, nobody thinks the public should get to view military exercises, and nobody thinks the public should sit in on cabinet discussions or that the confidential advice to cabinet should be public. I think there's a broad consensus among all who have been involved in government that there is a whole list of things--police investigations, confidential information, etc.--that is not public. I think everybody is willing to give the CBC a pass on disclosing its journalistic sources, for example.
On October 18th, 2011. See this statement in context.