The practise of outlining principles for the conduct of US security policy in so-called doctrines is a characteristic feature of US foreign policy. From an international lawyer's point of view two aspects of these doctrines are of particular interest. First, to what degree are the criteria for the use of force, as laid down in these doctrines, consistent with the limitations for the use of force in international law? Second, which law-creating effects do these doctrines have? Furthermore, the legal nature of these doctrines remains uncertain. These matters are examined, beginning with the Monroe Doctrine of 1823 and taking into account the Stimson Doctrine of 1932, the doctrines of the Cold-War period and the Bush Doctrine of 2002. The Bush Doctrine in particular has generated controversies concerning its compatibility with Article 51 of the UN Charter, due to its principle of preventive self-defence.