Zheyu guijian 折獄龜鑑

Zheyu guijian 折獄龜鑑 "A tortoise mirror for the solution of (difficult) cases", called initially Jueyu guijian 決獄龜鑑, is a collection of exemplary lawsuits compiled by Zheng Ke 鄭克 (fl. 1133) during the Southern Song period 南宋 (1127-1279). Zheng thought that He Ning's 和凝 (898-955) Yiyuji 疑獄集 was not detailed enough and, therefore, collected further material on controversial lawsuits and compiled his 8-juan-long book. The word "tortoise" in the title refers to the government and is based on a verse in the Classic Shijing 詩經 "Book of Songs" (ode Panshui 泮水), where it is said that "large tortoises" were delivered as a tribute to the king of Zhou 周 (11th cent.-221 BCE).

Zheng combed many books, so he came to such a vast number of cases that they are challenging to overlook. Nevertheless, the book attracted the attention of many scholars because it was the richest source of law cases in China until the Song period. Zheng's own sense of justice oscillated between "displaying virtue" and "using punishment only sparingly", so he was praised for his "mean way" (zhongdao 中道) of judgment. The full text of the book was quoted in the Ming-period 明 (1368-1644) encyclopaedia Yongle dadian 永樂大典, but the division between the individual fascicles was not copied. While the original text was divided into 20 juan or chapters, the compilers of the series Siku quanshu 四庫全書 arranged it into 8 juan. A supplement called Zheyu guijian bu 折獄龜鑑補 compiled by Hu Wenbin 胡文炳 (fl. 1849) is found in the series Qianyuan zongji 潛園總集.

In 1988, the Shanghai Guji Press 上海古籍出版社 published Liu Junwen's 劉俊文 commented edition Zheyu guijian yizhu 折獄龜鑑譯注. In the series Shuofu 說郛 and Longwei bishu 龍威祕書, the text is called Xiyu guijian 晰獄龜鑑. It is also found in the series Mingbianzhai congshu 明辨齋叢書, Mohai jinhu 墨海金壺, Shoushange congshu 守山閣叢書 and Congshu jicheng chubian 叢書集成初編.