International comity refers to deference to other countries that is not required by international law. The principle of international comity animates many different doctrines, which can be grouped into three categories: those that defer to foreign governments as litigants (“sovereign party comity”), those that defer to foreign lawmakers (“prescriptive comity”), and those that defer to foreign courts (“adjudicative comity”). Within each of these categories, “positive” comity doctrines use comity as a principle of recognition (such as the recognition of foreign judgments or the application of foreign law), while negative comity doctrines use comity as a principle of restraint (such as foreign sovereign immunity or the act of state doctrine).

When courts refer to the “doctrine of comity” or “comity abstention,” they often mean deference to parallel litigation in foreign courts or foreign bankruptcy proceedings. The Ninth and Eleventh Circuits, however, have invoked “international comity abstention” more broadly to dismiss cases based on foreign relations concerns.