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The Mutual Assistance and Solidarity Clauses

Legal and Political Challenges of an Integrated EU Security System


Antonio-Maria Martino

The Mutual Assistance and Solidarity Clauses is the first comprehensive comparative analysis of two major innovations introduced by the Lisbon Treaty. Antonio-Maria Martino’s study focuses on the origins, scope, interpretation and technical aspects of both clauses, with a particular focus on the Solidarity Clause. He highlights the overlap between both provisions and the wide range of competences theoretically conferred upon the Union by the Solidarity Clause. The author also presents a critical outline of the negotiations with regard to the new Joint Proposal on the implementation of the Solidarity Clause by the Union, which will set out the framework for EU action in the event of a solidarity case.
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The ‘Mutual Assistance Clause’ (Article 42(7) TEU)1 and the ‘Solidarity Clause’ (Article 222 TFEU) were formally introduced by the Lisbon Treaty2. Whereas the Mutual Assistance Clause has models such as the NATO Treaty3 and the modified Brussels Treaty of 19544, which established the Western European Union (WEU), the Solidarity Clause is a ‘genuine’ innovation of the European Union. Although the overall aim – assistance to a Member State affected by an extraordinary situation – is the same and the principle of solidarity underpins both provisions, there are legal differences and also possible overlaps between the two Clauses.

According to Article 5 NATO Treaty, an armed attack against one of the signatories is to be considered an attack against them all. Therefore, in line with Article 51 of the UN Charter, such an attack would give rise to the right to self-defence for all NATO Member States. Furthermore, Article V WEU states that the signatories are to support the attacked State with all the military and other aid and assistance in their power. The Mutual Assistance Clause in Article 42(7) TEU applies in cases of armed aggression by a third State and is notable for its brevity, simplicity and vagueness. With regard to its legal setting, the Mutual Assistance Clause is not the object of a separate article itself but is covered by Article 42 TEU. The Clause does not include any reference to implementing procedures or to operational mechanisms, nor does it give any role...

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