Abstract: Doubt pervades most laws, becomes alarming when it arises in criminal law, and seems especially discomfiting in the context of Islamic criminal law. In the high-stakes area of American criminal prosecutions, dubious facts or ambiguous laws can result in unjustified deprivations of life, liberty, or property. Criminal prosecutions in early Islamic contexts bore similar risks, which were compounded by the idea of a divine lawgiver who had outlined a set of fixed criminal laws and harsh punishments. In this system, there was no legislature to update the law, no high court to authorize departures from it, and no prosecutor charged with proving facts beyond a reasonable doubt. These features made-and continue to make--doubt in Islamic criminal law not only concerning but also ubiquitous.