Plaintiffs sued the defendant in a state court based on a motor accident, and the defendant removed to the federal court based on diversity of jurisdiction. Plaintiffs filed a motion to remand, based on the argument that one of the plaintiffs was a resident of South Korea although she is a U.S. citizen. The plaintiff who was a South Korean resident initially went to Korea to teach English, then got married to a Korean citizen. She was undecided as to whether she and her husband would stay in Korea permanently, but the couple had purchased a home in Korea and she was learning Korean more intensively to find a permanent job in Korea.
Based on these facts, the court found that the plaintiff was domiciled in South Korea rather than Louisiana. Because diversity jurisdiction cannot apply to U.S. citizen residing abroad, the court granted the motion to remand to state court.
Strangely enough, this fact always surprises me a little every time I see it: there is no diversity jurisdiction over a U.S. citizen domiciled abroad. Determining domicile is a fact-intensive exercise, which could be an interesting lawyering point if a war of attrition appears necessary.