Article IV, Section 3 of the United States Constitution states that states cannot secede from the U.S. through legal means.
However, some other countries allow legal secession. Why do some countries have rules in their constitutions that allow states to secede from the country through legal means? Is there any advantage in allowing such a thing?
Some examples of countries which have such provisions are (from comments):
- Northern Ireland has the ability to leave (after a referendum in both it and Ireland) the UK and join Ireland.
- The French Constitution provides for overseas territories to change their status by referendum.
- The UK has no written constitution, but many of its former territories have become independent (or in at least two cases been ceded to another state).
- The Saarland was transferred from France to Germany after a plebiscite.
- Niue and the Cook Islands are in free association with New Zealand and can terminate or alter this should they wish.