This paper identifies the ethical issues associated with college instructors’ use of plagiarism detection software (PDS), specifically the Turnitin program. It addresses the pros and cons of using such software in higher education, arguing that its use is justified on the basis that it increases institutional trust, and demonstrating that two common criticisms of such software are not universally valid. An analysis of the legal issues surrounding Turnitin, however, indicates that the way it is designed and operates raises some ethical (...) issues because it denies students notice, access and choice about the treatment of their personal information. The paper concludes with a set of guidelines for instructors using Turnitin in the classroom. (shrink)