The solidarity clause was drafted a year after the terrorist attack in New York in 2001 and was informally further substantialised after the terrorist attack in Madrid in 2004. It became evident that terrorism is also a real and current threat to the Member States of the EU. The solidarity clause is now a part of the Constitutional Treaty (CT), which at the moment is subject to ratification in the different Member States. The provision stipulates an obligation for the Member States of the EU to assist a Member State which is the object of a terrorist attack. The solidarity clause was intended to gather all EU instruments in order to combat terrorism in a flexible and efficient way. However, the general wording of the provision also results in some implications from a legal point of view. The character of the solidarity clause illustrates how it is at times difficult to establish the borderline between the political and legal aspects of EU. The solidarity clause appears to be merely a provision of political value ensuring that the Member States will assist each other in times of crises. In reality the solidarity clause, as a treaty provision under the jurisdiction of ECJ, includes a binding legal obligation. The main implication from a legal point of view is that the solidarity clause, and all the other provisions for that matter, is a product of a compromise reached by the Member States' delegations. The wording of the provision is therefore very general and vague. Since the application of the solidarity clause can lead to joint police and military activity the provision needs to provide some legal certainty. The current wording of the solidarity clause can give rise to conflicts if some of the Member States starts to consider the provision as a legal instead of merely a political obligation. The solidarity clause deals mainly with the horizontal relationship between the Member States. The provision does not explicitly confer rights to individuals and due to the general formulation it is not likely to have direct effect. The only way for ECJ to deal with the future implications of the solidarity clause is if there is an infringement of the provision as such, in other words if no assistance is provided or if a Member State considers that another Member State has not acted in accordance with the solidarity clause. Since the solidarity clause deals with politically sensitive issues and the obligation is mainly horizontal it is not unlikely that there will be an increase in the amount of cases where one Member State brings another before the ECJ. However, the ECJ has not previously been enthusiastic about dealing with politically sensitive issues. In the lack of further formal or informal more detailed arrangements in relation to the solidarity clause the potential conflicts have to be solved on a political level. Due to the fact that the solidarity clause includes, at least in theory, a potential military commitment the greatest impact on Swedish affairs will from a legal point of view be the difficulty in maintaining a policy if non-alignment. The CT contains an increase of supranational features, mainly in the area of freedom, security and justice. However, due to the mere existence of a solidarity clause and its focus on the intergovernmental relationship it can not be considered as step in the constitutionalisation of the EU.