Back v. Back
125 N.W. 1009 (Iowa 1910)


  • William Back got a divorce and then married his ex-wife’s daughter from a previous marriage (plaintiff here).
    • Thus, there was no blood relation.
  • When Back died, an issue arose for inheritance purposes as to whether the marriage was incestuous and void.
  • Under the provisions of Code, § 4936, the definition of “incest” includes marriage between a man and his wife’s daughter, and prohibits such marriage.

The trial court ruled that the marriage to plaintiff was void in its inception and continued to be void after the death of plaintiff’s mother and until the death of decedent, and that, therefore, plaintiff is not the widow of decedent.

Whether a marriage between a man and his ex-wife’s daughter from a prior marriage is incestuous and void.

No. Case reversed.


  • “We reach the conclusion, therefore, that the relationship of affinity between the decedent and plaintiff which existed during the continuance of the marriage relation between decedent and plaintiff’s mother terminated when the latter procured a divorce from decedent, and after that time plaintiff was not the daughter of decedent’s wife, and the marriage between them was valid.”
    • Note: Affinity = relations established by law, such as step families.
  • The relationship here was purely legal, thus the divorce solved any potential issues.
  • Prof: Consanguinity (blood) cannot be destroyed, while affinity (legal) can.

Rule: Relationship by affinity terminates with the termination of the marriage which gave rise to the relationship either by death or divorce, i.e., a man may validly marry the daughter of his ex-wife if the first marriage is legally terminated prior to the second marriage.