As a result of the new Christian focus on sexual behaviour driven by the Augustinian definition of the core reason for marriage, from the fifth century a new motif emerged which openly challenged a married man's right to have sexual contact with slaves and concubines, and redefined such behaviour as adultery. Throughout the classical Roman period, adultery was defined simply as the occurrence of a married woman having sexual contact with a man other than her husband. This is the definition of adultery that we see in the majority of post-Imperial legal texts. The earliest, and simplest, adultery laws deal exclusively with female adultery, in line with classical and late Roman law. Thus, in the Lib Con. it is punishable by the woman's immediate death at the hands of her husband or father along with her sexual partner. The Burgundian laws make the execution of the woman and her sexual partner at the hands of her husband the fundamental punishment and in fact, should he kill only one, or neither of the pair, punishes the husband with fines. This is in line not only with late Roman law (for example Dig. 4, 4, 37), but also with Augustus's Lex Julia de Adulteriis of AD 18, and the Cornelian law de Sicariis, derived from the Twelve Tables, which concerned homicide and was instituted by Sulla in BC 82. The Lib. Con. does contain a divorce provision for instances of female adultery, in which adultery is stated to be a cause for legitimate and unpunished divorce. This possibly suggests that a significant number of men did not instantly execute their wives regardless of the letter of the law. In such instances, the case is referred to a judge where the husband must prove the accusation of adultery and, should his wife be found guilty, the judge will ‘pronounce the letter of the law against her’ and she will be branded a ‘criminal’. So, the case presumably results in her execution by another means.

In the Lombard and Visigothic law codes the provisions for adultery are more detailed and more complex but are also broadly similar to the classical Roman law: a man has the full right to kill his wife and her partner if they are caught in an adulterous position.