In re Duchy of Sealand
Administrative Court of Cologne
Case No. 9 K 2565/77 (1978)
The Duchy of Sealand was a small, 1,300-square-meter former British military platform held up by concrete pillars, eight nautical miles off the coast in international waters and abandoned by Britain after World War II; people began living on it, with about 106 total inhabitants including 30-40 permanent residents. The plaintiff, a German citizen, received a document purporting to grant him Sealand citizenship, and asked Germany (defendant) to determine whether he had lost his German citizenship as a result; Germany determined he had not, reasoning Sealand wasn't a "state" under international law, and the plaintiff sued for a judgment that he had lost his German citizenship.
Whether a small, inhabited former military platform in international waters, whose residents form a loose collection of individuals rather than a genuine community, qualifies as a "state" under international law such that its purported citizenship displaces an inhabitant's prior national citizenship.