The German constitution of 1949 prohibits any war of aggression. The deployment of the military abroad is allowed only for purposes of defense and within the framework of a system of collective security. Under the latter heading, the German army has since the 1990s contributed to numerous collective military operations, ranging from UN-peace missions over NATO operations to anti-terror action. The contours of the constitutional regime are judge-made and, so far, based on four lead judgments since 1994, together with further case law. In the seminal judgment of 1994, the Constitutional Court identified a constitution-based requirement of parliamentary approval for each military deployment. The formalities of the involvement of the Bundestag were, in 2005, codified in a statute. The rationale of this requirement is to secure a democratic basis for every deployment, flowing from public deliberation and a vote in the parliament. The requirement has also served to counterbalance the development of the NATO treaty by the government under which NATO has extended its range of activities.
Recent German participation in coalitions of the willing against pirates and terrorists have raised the question whethersuch operations are still covered by the constitution, because they are neither traditional self-defense nor based on authorisations by the Security Council under Chapter VII.
The Constitutional Court can review whether a deployment decision by the government unduly curtails powers of the parliament or of a parliamentary faction and it has, through this lens, frequently examined the constitutional parameters of the use of force and, incidentally, also aspects of international law.
