In the early Tang, the Censorate (Yushitai 御史台) functioned effectively when the Three Bureaus Censors (Sanyuan yushi 三院御史), consisting of the Attendant Censors (Shiyushi 侍御史), the Palace Censors (Dianzhong shiyushi 殿中侍御史) and the Investigating Censors (Jiancha yushi 監察御史), were conscious of their responsibility to be "the eyes and ears of emperor, " and were able to supervise autonomously without being restricted by the chiefs of the Censorate (Taizhang 台長), consisting of a Censor-in-chief (Yushi dafu 御史大夫) and two Vice Censors-in-chiefs (Yushi zhongcheng 御史中丞). This autonomy had been preserved by the Attendant Censor for Miscellaneous Affairs (Shiyushi-Zhizashi 侍御史知雑事), the title awarded the longest-serving member of the Attendant Censors. As the head of the Three Bureaus Censors, the Shiyushi-Zhizashi had the authority to punish the Censors, which insured that the Three Bureaus could act autonomously. The appointment of Yang Shenjin (楊慎矜), who became Zhizashi during Emperor Xuanzong's (玄宗) reign, raised the status of the Shiyushi-Zhizashi. This can be proved by analyzing the names of the Shiyushi-Zhizashi engraved on the stone monument of the Censorate Temple (Yushitai jingshe bei 御史台精舎碑). At that time, punishment of the Three Bureaus Censors was ritualized. The procedures for carrying out the punishment were meticulously stipulated, and the reprimand of a censor was conducted in front of the other censors. This ritualization enhanced the authority of the Shiyushi-Zhizashi, who determined the punishment. In the second half of the Tang, the Shiyushi-Zhizashi whose authority had been heightened helped the chiefs of the Censorate strengthen their control over the operations of the Censorate. From mid- to late Tang, the chiefs of the Censorate further tightened control over the operation of the Censorate. Under the new system, the Shiyushi-Zhizashi was recommended by the chief of the Censorate, and was held simultaneously by the Langguan (郎官), consisting of the Directors (Langzhong 郎中) and the Vice Directors (Yuanwailang 員外郎) of the Twenty-four Bureaus of the Six Ministries (Liubu ershisisi 六部二十四司) and of the Left and Right Offices of the Department of State Affairs (Shangshu dusheng zuoyousi 尚書都省左右司). Under the influence of the chiefs of the Censorate, the Shiyushi-Zhizashi strictly controlled the Three Bureaus Censors by exerting the authority to punish them. It is well known that in the mid- and late Tang, the Censor-in-chief was not always appointed, while the Vice Censors-in-chief became the acting Censor-in-chief. Consequently, the Shiyushi-Zhizashi functioned as the Vice-chief, and was recognized as the Vice-chief within the bureaucracy. As a result of the tightening of control by the chiefs of the Censorate, the Three Bureaus Censors gradually deviated from the ideal of "the eyes and ears of emperor, " and lost their autonomous status. During the Five Dynasties, the rulers attributed the disorder of the Court to the malfunctioning of the Censorate. The Five Dynasties inherited the late Tang's system of the Shiyushi-Zhizashi, but the rulers of the Later Jin reinstituted the system in which the longest-serving member of the Attendant Censors was appointed as the Zhizashi. However, a few years later, the system reverted again to that of the late Tang, and the previously instituted reform turned out to be a failure. The two reforms in the Later Jin indicate the loss of the Three Bureaus Censors' autonomous status. Thereafter, the system was inherited by the Northern Song without any change, and the Shiyushi-Zhizashi was established as the Vice-chief. In the reign of Emperor Shenzong (神宗), the Shiyushi-Zhizashi was renamed Shiyushi (侍御史). The title of Zhizashi itself disappeared, and its functions were carried out by the Shiyushi.