At common law, perjury was considered one of the most odious of offenses. According to William Hawkins, perjury ‘is of all Crimes whatsoever the most Infamous and Detestable’. Under the Code of Hammurabi, the Roman law, and the medieval law of France, the punishment for bearing false witness was death; in the colony of New York, punishment included branding the letter ‘P’ on the offender's forehead. In recent studies of public attitudes toward crime, perjury continues to be viewed as a very serious offense. This chapter shows exactly what it is that makes perjury morally wrong, and how the contours of such moral wrongfulness shape the contours of the legal doctrine by which the crime is defined. It explains how an understanding of the underlying moral concept of ‘lying’ illuminates our understanding of the perjury case against Bill Clinton that was first mentioned in the Introduction.