Domestic obligations must rank among the most important of personal obligations, whether importance is judged by social significance, by the number of persons affected, or (in recent decades) by volume of litigation. They are private legal obligations in the strictest sense of each of these words, yet they have usually been marginalized in or omitted entirely from accounts of the law of obligations.

Anglo-American law, unlike some other systems, has not formally separated family relationships from the rest of private law. In the past some features have tended towards a separation, such as the exclusive matrimonial jurisdiction of the English ecclesiastical courts (abolished in 1857), the rule of interspousal immunity in tort law (abolished in the twentieth century), and a presumption against binding contractual relations in family agreements (never more than a presumption). In the second half of the twentieth century any possibility of a formal separation receded as property disputes between spouses were adjudicated by applying general principles of property law, contracts, torts, trusts, and unjust enrichment; sharp distinctions based on the status of marriage became untenable as the same principles were then extended to non-matrimonial relationships.

The omission of domestic obligations from accounts of private law cannot therefore be justified on formal grounds. They can neither be subordinated to any of the concepts just mentioned nor wholly separated from them.