You've asked this question 3 or 4 times and haven't offered your own proposal.  Thus, can we assume your posts are meaningless?  How about making anyone point of entry into Canada a point of entry where the law does apply.  Right now as  I understand it, refugees can be claim asylum by entering not an official border point.  Easy fix...make setting foot in Canada regardless of how or where an official entry point and thus they would be turned back to the US.