In the "Civil War Files" handbook that just came out there's a preface in the form of a letter from Tony Stark to the president talking about the Registration Act. One of the things he says:
Even Canadian legislators had no problem passing similar legislation, although their version of the Registration Act was eventually held unconstitutional by the supreme Court of Canada.
I assumed that this was pretty much forgotten by Marvel. Nice to see some of the latter-years AF stuff is still remembered.