The Channel Islands sit in the English Channel off the coast of France, but they are not part of France. Their history and politics are most amazing things, and I can hardly do better than point you all to the Wikipedia article. So go there, read at least the first two sections, and then come back here for one final anecdote (I don't vouch for its accuracy, which is why I haven't merged it into Wikipedia).
When at the height of the Napoleonic Wars the U.K. attempted to provide Guernsey with a Smuggling Act, the States of Guernsey protested that such an act was against the constitution of Guernsey, and therefore could be of no effect there. After all, it was the Channel Islands — as part of Normandy — who had conquered England, not the other way about.
In the end, a compromise was eventually reached whereby all instances of smuggling in the Channel Islands would be tried solely in local courts, whereas any other instance of smuggling outside the U.K. would be tried in the county of Middlesex, as usual. (At the time, piracy and smuggling were, formally speaking, committed "on the high seas in the county of Middlesex".) As you can well imagine, there were no convictions, and the trade routes between England and France remained open.