It wasn't legal for the US to separate from England either. Just hypothetically, say Alberta ultimately decides to separate and proclaims their independence. Th

It wasn't legal for the US to separate from England either. Just hypothetically, say Alberta ultimately decides to separate and proclaims their independence. They stop paying into the federal system and set up their own federal government. Ottawa says they will intervene with military force, but the US protects the separatists. This is not a likely scenario, but it's not at all impossible either.