A gunman intends to shoot and kill Victim. He shoots and misses his target, but the gunshot startles a group of water buffalo, causing them to trample the victim to death. The gunman brings about the intended effect, Victim’s death, but in a “deviant” way rather than the one planned. This paper argues that such causal structures, deviant causal chains, pose serious problems for several key legal concepts. -/- I show that deviant causal chains pose problems for the legal distinction (...) between attempts and completed crimes, and also for the distinction between attempts and mere preparations. I then suggest that cases of deviant causation undermine notions of legal liability for completed crimes in terms of actus reus and mens rea, and argue that natural accounts of negligence misclassify some cases involving deviant causal chains. After diagnosing several conceptual vulnerabilities in the law revealed by deviant causal chains, I show that natural strategies for shoring up legal theories in the face of these examples are unpromising. (shrink)