I will jump in and add my two cents.
To build a bit on what David said, I agree that it's certainly a complicated question. I think there are inherent limitations in the ability of domestic legislation, obviously, to govern what happens to information once it's in the hands of other sovereign governments. That has always been an issue.
There are at least a couple of things that traditionally we've done. One of them David alluded to, which is being careful with who we share things with and being careful with how much we share. Part of that involves some understanding of the nature of the foreign governments, the way they operate, and the type of civil liberty protections they offer to their own citizens as well as to foreign citizens. We can be somewhat choosy in how we share, with whom, and how much.
The second thing that I think Canada has traditionally done is through the treaty process. We'll have treaties with various governments that will help govern how information is shared, pursuant to procedural safeguards, etc.