The yushi dafu 御史大夫, translated as Censor-in-chief, was the highest-ranking state official supervising and controlling the officialdom of the empire. During the early decades of the empire the office of Censor-in-chief was only second to the Counsellor-in-chief (chengxiang 丞相) but gradually transformed into the highest position of the institution of the Censorate (yushitai 御史臺). The Censors of the Former Han period 前漢 (206 BCE-8 CE) were practically Vice Counsellors and often took part in important political decisions. The staffs of the Counsellor and Censor were called the "two ministries" (erfu 二府). The position of Censor often served as a springboard to that of Counsellor. Its nominal salary was 2,000 shi 石 "bushels" of grain mid-level. All memorials to the throne had to pass the office of the Censor before being processed, and all edicts issued by the emperor were to be countersigned by the Censor before being promulgated and transmitted to the Counsellor and the regional governments. The Censor so served as a person to check the influence of the Counsellor.
The control of officialdom by the Censor meant that he was allowed to indicate corrupt or illegal practice of each state offial and to interview officials charged of misdoings. His assistant was the Palace Aide to the Censor-in-chief (yushi zhongcheng 御史中丞, or Vice Censor), several attendant censors (shi yushi 侍御史) and bandit-suppressing censors (xiuyi yushi 鏽衣御史). The task of the Vice Censor was to supervise the regional inspectors (cishi 刺史) and the regional governors (taishou 太守) and magistrates (ling 令) directly, and to investigate the court officials. He was also to supervise all punishments of state officials. The 15 attendant censors had the main task to indicate misdoings of state officials and to initiate arrest and interviewing of suspects. Bandit-suppressing censors were only appointed in case of need and supervised the suppression of rebellions.
In 8 BCE the office of Censor-in-chief was renamed Grand Minister of Works (da sikong 大司空) and became one of the Three Dukes (sangong 三公). Position and salary of the Censor were concurrently raised to a level equal to that of the Counsellor and the Minister of War (da sima 大司馬). Between 5 BCE and 1 BCE the office was again given the former name. At the end of the Later Han period 後漢 (25-220 CE) the warlord Cao Cao 曹操 (155-220) abolished the Three Dukes and reinstated the offices of Counsellor and Censor. During the whole Later Han period the tasks of the Censorate were managed by the Vice Censor, while Censor-in-chief was just a honorific title. For a short time during the Wei period 曹魏 (220-265) the Vice Censor (acting as chief Censor in fact) was called gongzheng 宮正 "Rectifier of the palace".
The Northern Wei 北魏 (386-534) called this office zhongwei 中尉 "Commandant of the palace". From the Sui period 隋 (581-618) on the Censor-in-chief was reinstated in his former position of head of the Censorate. The Vice Censor was renamed from yushi zhongcheng to yushi dafu. This was no problem because the term and office of yushi dafu had been abolished at the end of the Han period. This means that the nominal Vice Censor who had acted as Censor since that time, was now called by a term corresponding to his real function, namely that of Censor-in-chief. The new Vice Censor was called zhishu shi yushi 治書侍御史 "secretarial censor", yet the early Tang dynasty 唐 (618-907) changed this title into the former designation of yushi zhongcheng.
Between 662 and 670 the Censorate (yushitai) was renamed Xiantai 憲臺. Empress Wu Zetian 武則天 (r. 690-704), enacting deep reforms of the central government, renamed the Censorate Suzhengtai 肅政臺 and divided it into two departments (left and right), each headed by a suzheng dafu 肅政大夫 "Censor-in-chief" who was assisted by a sixian dafu 司憲大夫 "Vice Censor". The left Censorate controlled the the officials in the capital and the metropolitan military officials, while the right censorate controlled the civilian and military officials in the provinces. These two departments were renamed yushitai in 705 but were only reunited in 712 as before.
The Censorate of the Tang empire consisted of three departments, namely the Headquarters Bureau (taiyuan 臺院), the Palace Bureau (dianyuan 殿院) and the Investigation Bureau (chayuan 察院). The Headquarters Bureau was headed by four to six attendant censors (shi yushi) who controlled the state officials and interrogated criminals. This bureau also controlled the income and expenditure of the capital granaries (taicang 太倉) and the Left Vault (zuocang 左藏) of the Court of the Imperial Treasury (taifusi 太府司). They were to see to that no funds was acquired illicitly entered the state treasury and no ransom pay. It was especially the so-called attendant censor of miscellaneous matters (zaduan 雜端) who practically exercised unrestricted powers. The Palace Bureau was managed by nine palace censors (dianzhong shi yushi 殿中侍御史) who supervised the arrangement of the officials during court audiences (chaoban 朝班) and the imperial regalia (yizhang 儀仗).
Within the capital they oversaw the police forces inside the capital who cared for law and order on the streets and the markets. Generally, members of this bureau also assisted the Headquarters Bureau. The Investigation Bureau was managed by fifteen investigating censors (jiancha yushi 監察御史) who controlled all officials and inspected the various provinces, prefectures and districts. They also managed all forms of punishment and jails. In their function of inspectors of the local government they were given several functional titles according to their task, like touring censorial inspector (xun'anshi 巡按使) when inspecting provincial (dao 道) government, or postal inspector (guanyishi 館驛使) when inspecting courier stations. They were sent out to inspect booty and war prisoners or military success and failure.
They oversaw the creation of military agro-colonies (tuntian 屯田) and the production of coins, and some inspectors cared for the pacification of the unruly mountain tribes of the southwest. In the central government, they were especially entrusted with the investigation of the Six Ministries (liubu 六部) and also assisted the Palace Bureau in the management of the imperial regalia. Among all these various tasks, the autonomous impeachment of officials and the exaction of punishment were the most outstanding issues. Officials of the Censorate did not to have ask for permittance of higher authorities for impeachment and were even allowed to impeach their own collegues. The Censor-in-chief himself was to be investigated by the vice directors (cheng 丞) of the Imperial Secretariat (shangshusheng 尚書省), at least in theory.
Legal matters could be brought directly to the court through the Palace Secretariat (zhongshusheng 中書省), supervising secretaries (jishizhong 給事中) and the Censorate, or by submitting a report to the Censorate by putting it in a petition box (ligui 理匭). In 648 the Censorate became its own prison. Before that date, prisoners were interrogated and held in the jail of the Court of Judicial Review (dalisi 大理寺). All censors were allowed to arrest and put into jail whoever was charged with a crime. This right made the Censorate a powerful tool in the hands of rulers who wanted to get rid of opponents, and it was a well-used tool during the reign of Empress Wu who entrusted Lai Junchen 來俊臣 with the suppression of her critics.
Although the Censors and their assistants occupied not a very high position in the hierarchy of state officials they wielded great power and had a deep influence on the whole officialdom, but also on financial affairs, like Yuwen Rong 宇文融, Yang Shenqin 楊慎矝, Wang Hong 王鉷, Yang Guozhong 楊國忠. All mighty officials of the empire concurrently were given the title of assistant censor or Vice Censor. These "outsiders" that not really belonged to the proper staff of the Censorate were called the "Outer Bureau" (waitai 外臺). During the late Tang period these purely vain titles mushroomed throughout the empire, and virtually all military commissioners (jiedushi 節度使) in the various provinces were concurrently called with the title of Censor. With the decrease of the imperial power after the rebellion of An Lushan 安祿山, that of the Censorate also declined. The right to inspect troops had been usurped by the eunuchs that controlled the central government, while the local government was in the hands of the military governors (fanzhen 藩鎮). In the early 9th century the Censorate had lost its control over all jurisdictional matters.
While the main Censorate was in the capital Chang'an 長安 (modern Xi'an 西安, Shaanxi), there was a second Censorate (liutai 留臺) in the eastern capital Luoyang 洛陽 (modern Luoyang, Henan) that was especially useful when Emperor Gaozong 唐高宗 (r. 649-683) and Empress Wu Zetian moved the court to Luoyang. With Emperor Zhongzong 唐中宗 (r. 705-709) returning to Chang'an, the eastern Censorate was gradually dissolved and only rudimentarily staffed.
The Song dynasty 宋 (960-1279) inherited the structure of the Censorate from the Tang empire, yet there was no yushi dafu and instead, the Vice Censor took over the post of chief censor. His lieutenant was the associate or "general purpose" censor (shi yushi zhi zashi 侍御史知雜事, short zhiza yushi 知雜御史).
Officials that had just started their career in the Censorate were given the suffix "on probation" (lixing 裏行). There were also some auxiliary investigators (tuizhiguan 推直官) in the Song period Censorate. Around 1020 the office of Remonstrating Censor (yanshi yushi 言事御史, also called jianguan yushi 諫官御史 or yanshiguan 言事官) was created and newly institutionalized in 1045. The traditional separation of censorial functions between remonstrance officials (jianguan 諫官) and surveillance officials (chaguan 察官) became therewith obsolete. In 1080 the former situation was created, yet the Censorate was rearranged according to the Six Ministries, and six investigation sections (liu'an 六案) were created whose staff had to control the officials of the respective ministry as well as the ressorts of other central government agencies that were organised in a similar way with six departments.
The Section for Revenue (hu'an 戶案) soon also took over the task to control the transport commissioners (zhuanyunshi 轉運使), the Section for Justice (xing'an 刑案) supervised the judicial commissioners (tidian xingyu 提點刑獄). The Section were in the beginning headed by three Censors, each heading two resort, but later on a Censor was created for each Section. Three other censors functioned as remonstrating censors controlling the department of the palace library (bishusheng 祕書省 or mishusheng 秘書省) and the palace domestic service (neishisheng 内侍省). In 1084 the associate censors (zhiza yushi) was renamed (shiyushi) and the remonstrating censor (yanshiguan) was renamed palace censor (dianzhong shiyushi), as before. The six investigating officials (chaguan) were renamed "investigating censors" (jiancha yushi). The offices on probation and those of auxiliary investigators were given up.
The stucture of the Censorate remained in place during the Jin 金 (1115-1234) and Yuan 元 (1279-1368) periods. The Ming dynasty 明 (1368-1644) replaced the title yushi dafu (Censor-in-chief) by duyushi 都御史, and that of the yushitai (Censorate) to duchayuan 都察院. This was in 1682, when eight Chief investigating censors (jiancha du yushi 監察都御史) were appointed that toured the twelve provinces (dao 道) of the empire. In each province, 3 to 5 censors took over surveillance of the officialdom. In 1383 the position of the Censorate was considerably promoted by an increase in rank (from 7A to 3A, soon even 2A) and was two Censors-in-chief (left and right duyushi 都御史), two Vice Censors-in-chief (fu duyushi 副都御史), four Assistant Censors-in-chief (qian duyushi 僉都御史), and a staff of registrars (jingli 經歷) and administrative clerks (zhishi 知事). Between 1400 and 1402 the name of the Censorate was changed from duchayuan to yushifu, yet the Yongle Emperor 永樂 (r. 1403-1424) change the name back to the new designations. In 1425 the provincial censorates were called branch departments of the Censorate (xingzai duchayuan 行在都察院) and were administratively put side by side with the provincial branches of the Six Ministries. The number of censors in each province was fixed in the next decades, yet the offices could also be taken over concurrently by supreme commanders (zongdu 總督) or grand coordinators (xunfu 巡撫).
The general structure of the Ming Censorate remained intact during the Qing period 清 (1644-1911).
The imperial Censorate, in existence until the end of the Chinese empire in 1911, was the model of the Control Yuan (jianchayuan 監察院) of the Republic of China.