Obligation to investigate
Article 20
1. Member States shall ensure that an investigation is carried out by the investigating body referred to in Article 22 after any serious accident on the Union rail system. The objective of the investigation shall be to improve, where possible, railway safety and the prevention of accidents. 2. The investigating body referred to in Article 22 may also investigate those accidents and incidents which under slightly different conditions might have led to serious accidents, including technical failures of the structural subsystems or of interoperability constituents of the Union rail system. The investigating body may decide whether or not an investigation of such an accident or incident is to be undertaken. In making its decision it shall take into account: (a) the seriousness of the accident or incident; (b) whether it forms part of a series of accidents or incidents relevant to the system as a whole; (c) its impact on railway safety; and (d) requests from infrastructure managers, railway undertakings, the national safety authority or the Member States. 3. The extent of investigations and the procedure to be followed in carrying out investigations shall be determined by the investigating body, taking into account Articles 21 and 23 and depending on the lessons it expects to draw from the accident or incident for the improvement of safety. 4. The investigation shall in no case be concerned with apportioning blame or liability.