The American declassification system is really quite complicated and there are various categories, and I'm not as familiar with that system as I am with the British system. In the British system, there is a legislated requirement that government records be reviewed after 30 years and in large part declassified and transferred to their National Archives. There are some exceptions for materials to be retained for longer than that, but it's a general practice that once they're 30 years old, they are transferred to the archives.
The difference in the U.K. is that when they're transferred to the archives, they're automatically open, whereas in Canada, many of the government records that are transferred to the archives are still restricted. Therefore, LAC has to consult with the originating departments on whether they can be released. It's a much more complicated process.