1. It is permanently forbidden for a man, due to affinity, to marry: a. His wife’s ascendants, even if they ascend. b. The descendants of his wife with whom he had intercourse, even if they descend. c. Whoever is the wife of one of his ascendants, even if they ascend, or the wife of one of his descendants, even if they descend. 2. Entering into an invalid marriage entails the same consequences of prohibitions due to affinity in a valid marriage.
Interpretation and application must be checked against the official text and current version.