In response to Tacky’s Rebellion in 1760 in Jamaica, the colony’s House of Assembly passed a law naming a new crime, “obeah.” This important statute led the way in establishing obeah as a phenomenon understood by colonial authorities as a singular and dangerous problem. Investigating the Jamaica assembly’s decision within a wider Caribbean and Atlantic context and alongside the near-contemporaneous “Makandal conspiracy” in Saint Domingue, which was interpreted by French planters as a mass outbreak of poisoning, shows how similar practices came to be interpreted and constructed in different ways in different colonial cultures. The practices used by Tacky’s “obeah man” and Makandal’s followers were conceptually and practically similar, deriving from African understandings of medicine in which substances could be imbued with spiritual power. Why, then, did the French colonists emphasize poison while the British emphasized obeah (which they glossed with the term “witchcraft”)? In addition to the differences between developments in the colonies, an important context for understanding this distinction was the European experience of the decriminalization of witchcraft. In France decriminalization led to heightened anxiety about poison, while in England witchcraft decriminalization was not connected to poison but made the term and legal category of witchcraft a difficult one for planters to invoke.