The introduction of the right to plea bargain in June marks a major development in the nation's criminal justice system. The incoming system will enable prosecutors to not indict or file less serious charges against suspects or defendants who cooperate with investigations by offering testimony or evidence against their accomplices — but it will not be applied to suspects or defendants who agree to plead guilty to their own crimes in return for concessions from the prosecution. There are expectations that the system will serve as a useful tool in investigating organized crimes. However, there are also concerns that it could trigger false statements by suspects or defendants against others in seeking leniency for themselves, possibly leading to bogus charges brought against innocent people. The system must include sufficient measures to prevent such abuse.

Plea bargaining exists in varying forms in a number of countries. In the United States, where the system is said to have been in use for roughly 200 years, plea bargaining plays a major role in the criminal justice system. About 90 percent of criminal cases are settled through plea bargaining thus avoiding a lengthy trial process and helping to reduce the huge backlog of criminal cases. Most of the plea bargaining taking place in the U.S. reportedly involve defendants pleading guilty to their own crimes in return for leniency from prosecutors, such as indictment on lesser charges.

In Japan, the system is being introduced as an enhanced tool of investigation as part of broader criminal justice reforms. What triggered the reforms was a series of cases involving false charges being brought against innocent people. The police and prosecutors came under heavy criticism for investigations that relied heavily on the confessions of suspects — who were occasionally coerced or led by interrogators into make statements that supported the investigators' cases.