In this article authors focus their attention to one of the key principles of the European Union - the principle of subsidiarity. In introduction they refer to the European Union as a sui generis entity not just speaking in terms of its organizational structure but also in terms of distribution of power within it. In this line they consider the principle of subsidiarity. In the second part of the paper, authors focus their attention to arrangements provided by the Maastricht Treaty - which introduced the principle of subsidiarity, the Amsterdam Treaty, the Draft on the Constitution for Europe and, at last but not at least, to the Lisbon Treaty. Having on mind significant changes introduced by the Lisbon Treaty regarding the principle of subsidiarity, this treaty has a special place.