Amid the ongoing global biodiversity crisis , a key policy mechanism for species conservation is to establish and enforce scientifically grounded rules to define whether harmful activities—such as poaching, trade, and habitat destruction—constitute criminal behavior and should be convicted . China in recent years has made multiple amendments to its conviction criteria for crime on terrestrial vertebrates, including changing the basis of the criteria from the numbers of animal individuals involved in a given offense to their monetary values . As we demonstrate with a new analysis on all of China’s 522 protected bird and terrestrial mammal species, for the vast majority of species assessed, these amendments have meant that substantially greater numbers of individuals are now required for a given offense to be deemed convictable, and overwhelmingly at reduced penalty severities. The resultant risk of weakened crime deterrence has been evidenced by judicial outcomes and observations of conservation practitioners.