Where it has exclusive competence, the EU alone has the power to negotiate and conclude the agreement. Moreover, Article 3 of the Treaty on the Functioning of the EU specifies the areas in which the EU has exclusive competence to conclude international agreements.
Where its competence is shared with Member States, the agreement is concluded both by the EU and by the Member States. It is therefore a mixed agreement to which Member States must give their consent. The areas in which competences are shared are defined in Article 4 of the Treaty on the Functioning of the EU.