看一下加拿大在95年魁北克独立公投后，修改了法律，单边宣布独立是非法的

Supreme Court of Canada, which followed Federal intervention post-referendum into the Bertrand case: The 1998 Reference Re Secession of Quebec stated that unilateral secession was illegal, would require a constitutional amendment, and that only a clear majority on a clear question could bring about any sort of obligation on the federal and provincial governments to negotiate secession.