[burfog]

It may be politically impossible, but it isn't legally impossible.

Laws, including constitutions, can be changed. This works for both sides of the border. Killing NAFTA is an easy start. Canada can have a wall to keep people in without even building it: simply lobby US politicians to have one built.

[okfine]

I meant impossible under the Charter of Rights, which could change, but isn't going to. You're right that that's for political and not legal reasons, so "politically and legally impossible" is in a way redundant. In another way it isn't, though, since constitutions do constrain politicians.