Marriage posed problems of immense complexity for medieval canonists. They had the unenviable task of providing guidelines for how to partake in a complex, weighty, and dangerous matter. Marriage was considered sacred, divinely sanctioned, but at the same time it was all too worldly, rife with the risk of committing grave sins. Competing notions of how best Christians should marry in compliance with the teachings of the Old and New Testaments posed problems enough to cause endless difficulties for canonists. Even more problematic, if anything, was the fact that marriage was of immense importance in their society, a bedrock of social, economic, and political organization. All this led to myriad competing concerns. The solutions posed by medieval popes and canonists have had a mixed reception. They certainly failed to impress sixteenth-century reformers.

A genuine canon law of the family developed in the high Middle Ages. It was built on papal decisions in specific cases during the second half of the twelfth century and the first decades of the thirteenth, and their interpretation by professors of law. Academic exposition was crucial in this legal field, more so than in others, since ecclesiastical legislation in the first millennium had taken little or no interest in the family. Church courts were largely forced to innovate, seeking papal verdicts and generating many papal rescripts that required interpretation by the masters. As was their wont, the ecclesiastical judges and the canonists also borrowed many rules from Roman law in order to fill the holes in canon law, which happened to touch only incidentally on certain questions, such as guardianship and adoption, and disregarded others entirely, such as emancipation.