This article is based on a corpus of transcripts of four criminal courtroom trials in China. It investigates interruption in the Chinese criminal courtroom discourse as a highly institutionalized and strongly goal-oriented discourse. The study focuses on the number, functions, causes, and distribution of interruptions as well as their correlation with the Chinese legal system and legal culture. Interruptions in Chinese courtroom trials are substantially asymmetrical in terms of the number, functions, and causes in the sense that prosecutors interrupt the most and defense lawyers the least, with judges being in the middle but somewhat closer to prosecutors. A defendant is the most interrupted party. The dominant side, represented by the judge and the prosecutor, interrupts to exercise control by stretching the Gricean maxims to the extreme. In contrast, a defendant interrupts mainly for cooperation or to insist on their right to speak. I also attempt to explain the imbalance by referring to the Chinese judicial system and legal culture and compare the interruption phenomena in Chinese criminal trials with those I observed in the United States.