With sentence no. 834 of 15 January 2019, the Court of Cassation has again ruled on a subject widely discussed in doctrine and jurisprudence: the difference between emendatio and mutatio libelli. In summary, according to now stable jurisprudence of the Supreme Court (see, on this point, ex plurimis, Court of Cassation no. 12621 of 20 July 2012 ; Court of Cassation no. 1585 of 28 January 2015), mutatio libelli is present if, during the course of the trial, one of the parties advances a claim objectively different from the original, so introducing to the trial, a different petitum or causa petendi based on constituent facts radically different and never before put forward. The result is that the Judge is presented with a completely new area for investigation, thus overturning the system of preclusions proper to the civil trial. On the contrary, there is a simple emendatio to the initial claim if it is only specified or otherwise quantified, without prejudice to the constituent facts on which it is based.
This distinction is of great practical importance since, as already mentioned, the code of practice provides for certain specific preclusions with regard to the submission of new claims during the course of the proceedings. And indeed, on the one hand, as far as the trial of first instance is concerned, they must be carried out imperatively within the term referred to in Art. 183 , para 6, no. 1 of the Code of Criminal Procedure, and, on the other hand, as far as the judgment of appeal is concerned, Art. 345 of the Code of Criminal Procedure expressly prohibits the parties from advancing new claims.