Four legal usages of abduction can be distinguished: the inference from facts to norms, the inference from norms to principles, the inference from facts to facts and the inference from characters to concepts. A description of what C.S. Peirce in-tended by abduction and a brief account of the philosophical debate about it pre-cede the analysis of these usages. This analysis is followed by the suggestion of three models of legal reasoning issuing from the legal role of abduction and from Peirce’s conception of scientific methodology.