The topic of this article is the evolution of chosen principles of Polish criminal procedural law. Analysing individual principles is important because they establish the model of criminal proceedings. The change of individual principles causes the modification of the procedural model established earlier. The Author, analysing the introduced changes in law, distinguishes principles which were strengthened. These principles are the principle of legalism and the adversarial principle. In the Author’s opinion, as a result of the introduced changes there have been some limitations in the execution of the principle of equality of parties. This is the result of the strengthening of the role of the prosecutor in court proceedings. The principle that has been in practice marginalised is the principal of the participation of lay judges in adjudication.