A system for trial by jury was first introduced in 1923 under Prime Minister Katō Tomosaburō's administration. Although the system generated relatively high acquittal rates, it was rarely used, in part because it required defendants to give up their rights to appeal the factual determinations made. The system lapsed by the end of World War II. In 2009, as a part of a larger judicial reform project, laws came into force to introduce citizen participation in certain criminal trials by introducing lay judges. Lay judges comprise the majority of the judicial panel. They do not form a jury separate from the judges, like in a common law system, but participate in the trial as inquisitorial judges next to professional judges in accordance with the civil law legal tradition - similar to the French cour d'assises - who actively analyze and investigate evidence presented by the defense and prosecution. Current system On May 28, 2004, the National Diet passed a law requiring selected citizens to participate as judges (and not juries) in trials for certain severe crimes. Citizens chosen for such service, called , are randomly selected out of the electoral register and, together with professional judges, conduct a public investigation of the evidence in order to determine guilt and sentences. In most cases, the judicial panel is composed of six saiban-in and three professional judges. In cases where there is no substantial dispute over guilt, the panel is composed of four saiban-in and one professional judge. Unlike under the older jury system, the defendants are not allowed to waive trial by saiban-in. The saiban-in system was implemented in May 2009. Process In many respects, the new system is very different from a common law jury system. It is not a (lay) jury of an adversarial system of common law but one that involves a (lay) "judge" found in inquisitorial systems of civil law countries, such as those in continental Europe and Latin America. In a common law adversarial system, the judge acts as a referee over the contest between the defence attorney and the prosecutor, in which the two sides present the facts of their case to the panel of jurors; the judge in this system is mainly the referee of court procedure and decides only the applicable law. In the civil law inquisitorial system, the entire panel of judges conduct a public investigation of the crime at the trial,