The subject of the investigation is international treaties that the member states of the European Union concluded with third countries prior to their accession, known as pre-Community agreements. Article 307 EC regulates the situation where pre-Community agreements are not in accordance with European law. Following the historic accession of ten states to the European Union on May 1, 2004, it is expected that such incompatibilities will need to be resolved based on Article 307 EC. The author presents the key statements of the case law regarding pre-Community agreements, including the GATT case law of the Court of Justice of the European Union. He addresses the question of whether the solutions provided by the case law can be reconciled with international law. Building on this, he develops principles for the application of Article 307 EC, which could soon be significant for practice.