The term State of Defence (in German: Verteidigungsfall or V-Fall) refers to the legal status of the Federal Republic of Germany if it is "under attack by armed force or imminently threatened with such an attack". Themail special status, which was created by a constitutional amendment in 1968, gives the Federal government extraordinary powers in wartime. It is laid down in Articles 115a to 115l (Title Xa) of the German Constitution. As of January 2017, Germany has never been in the State of Defence.
According to article 115a of the German Constitution, the State of Defence shall be declared if "the federal territory [of the Federal Republic of Germany] is under attack by armed force or imminently threatened with such an attack".
The normal procedure is that, upon request of the Federal Government, the Bundestag determines that the conditions of the State of Defence exist. That means that the Bundestag does not actually declare the State of Defence; instead, it just decides whether it exists or not. (If, for example, a foreign army invaded Germany, the Bundestag would determine that the action is an "attack by armed force", as described in article 115a, and so Germany is in the State of Defence.) The determination requires at least two thirds of the votes of the Bundestag present at that time (at least half of the members being the quorum). It also has to be approved by the Bundesrat with an more than half of its members, which, according to general Bundesrat protocol, is given in bundled form by each Land.
If the Bundestag or the Bundesrat is not able to convene in time or not able to reach a quorum, the Joint Committee decides on their behalf.
If Germany is under attack by armed force and the Bundestag, the Bundesrat and the Joint Committee are not able to determine the State of Defence immediately, "the determination shall be deemed to have been made and promulgated at the time the attack began". If, for example, an invasion started on January 4 at 4:17 a.m., Germany would be in the State of Defence from that time, and the government could react immediately.)