During the legal revision process of the late Qing and Republican eras, basic homicide categories were condensed from six to two, resulting in a simpler categorization than had been in place during the Qing. One of the categories that remained was guoshi killing, defined as negligent homicide in the Republican era. This article compares the treatment of guoshi killing in both the Qing and the Republic in legal codes, commentaries, and cases. It finds that the streamlining of Republican homicide categories brought crimes of intent and negligence into confusion for the first time. The troubles the Republican-era courts encountered as a result help to illuminate the nuance and sophistication of the system that had come before.