Close cohesion of family and some other hierarchical groups in China, on the one hand, and the Confucian doctrine, on the other, stipulated broad use of the collective responsibility in the traditional Chinese criminal law. One of its most essential kinds was the mutual responsibility of fellow-offi cers. It implies returning guilty of all colleagues of the functionary who had made a mistake or had committed a crime. The machinery of the mutual responsibility was carefully elaborated in the criminal legislation of the Tang dynasty. The criminal himself was always esteemed the main guilty; all his colleagues considered the accessories of second, of third and of fourth degrees. So they received a punishment diminished on 1, 2 or 3 degrees as compared with the main criminal. The responsibility could be diffused to other institutions. However, if one of the colleagues disclosed and corrected an error, all of them were exempted from the responsibility. The system of mutual responsibility was a potent factor for strengthening of the corporate spirit within the offi cialdom and mutual supervision in state institutions of traditional China.