In this paper we set out to address general issues of legal liability, starting from the principle of responsibility in the matter of the General Theory of Law and up to legal liability under national law, public international law and European Union law.

Legal liability under national law does not exhaust the subject, in the field of international society the liability of states can be engaged – Project Articles of 2001 prepared by the International Law Commission within the United Nations, but also the liability of intergovernmental organizations – Project Articles 2011.

A controversial issue, both at the normative and doctrinal level, remains the international legal responsibility of the person - as individual.

Legal liability under European Union law lies primarily with States for failing to fulfil their obligations under the European Union law, through the infringement procedure, and other types of legal liability that exist at the Union level.

In order to strengthen the concept of legal liability, in the light of those promoted by the European Union, the European Commission, whose main task is to ensure the full application and observance of European Union law, and the Court of Justice of the European Union through its extensive case-law, have played a special role.