Foreign direct investment falls under the scope of the common commercial policy, a competence exclusively defined for the Union by the Lisbon Treaty. Bilateral investment treaties are also encompassed within the realm of foreign direct investment. Within the context of the European Union, this area is also important from the perspective of completing the EU's internal market. EU Member States have been, and continue to be, parties to numerous bilateral investment treaties. The present article aims to delineate the effects of the Lisbon Treaty on bilateral investment treaties, both intra- and extra-EU, and to present the status quo of this area under analysis within the European Union. A partial objective is also to scrutinize the potential impact on practice and assurances afforded to investors within the Union.