Family law — the body of statutes, case law, and legal doctrine governing marriage, parentage, divorce, custody, domestic violence, inheritance, and the rights of family members — was built for a social world that no longer exists in the way it once did. The social world it was built for had stable marriages, clear biological parentage, defined gender roles, children raised by their biological parents in a single household, and a clear distinction between the family inside which obligations ran and the world outside it, to which no comparable obligations applied. That world has not disappeared, but it has become one among several social arrangements rather than the default to which all others are exceptions.

Contemporary American families include: single-parent households constituting more than a quarter of households with children; stepfamilies and blended families in which parental roles are distributed among biological, legal, and functional parents who may not share a household; same-sex couples with children through assisted reproduction, adoption, or prior relationships; cohabiting couples with children who never marry; intentional multi-adult households that include both romantic and non-romantic relationships; older adults aging in households organized around friendship and mutual care rather than conjugal partnership; and individuals whose primary care networks are constituted by chosen-family relationships with no legal recognition at all. The law, built on the nuclear-family model, maps poorly onto most of these arrangements and not at all onto some of them.

The friendship dimension of family law reform is the dimension that has received the least sustained attention. The reform agenda that has received the most attention — marriage equality, parental rights for same-sex parents, legal recognition of stepparent relationships, protection for domestic partnerships — has been primarily organized around romantic partnership and biological or adoptive parentage. The friend — the person who constitutes a genuine care relationship with another adult, who provides mutual support over years or decades, who may function as the practical equivalent of family without the romantic or parental dimension — remains largely outside the reform agenda even as the other categories are progressively being addressed.

The gap between social reality and legal framework in family law is not merely inconvenient; it is harmful. When family medical leave applies only to biological and legal family members, the friend who takes time off work to care for a dying companion is doing so without legal protection. When hospital visitation rights are limited to family members, the friend who has been the daily companion of a hospitalized person may be excluded by a biological family member who appears at the hospital for the first time. When intimate partner violence law protects only people in romantic relationships, the friend who is being stalked or threatened by someone with whom they share a domestic relationship — whether romantic or not — may lack the protection that domestic violence statutes provide. When adoption law requires the termination of parental rights before a new parent can be recognized, the complex multi-parent arrangements that some families actually use cannot be legally accommodated.

The reform of family law for the 21st century is both a technical legal project and a cultural one. The technical legal project involves specific statutory and doctrinal changes: expanding FMLA definitions to include chosen-family caregiving; revising intestate succession to accommodate chosen-family relationships; developing legal frameworks for multi-parent families; creating legally recognized statuses for non-romantic chosen-family relationships; reforming hospital visitation and healthcare proxy laws. The cultural project involves changing the social understanding of what family law is for — shifting from the model in which family law regulates the biological and legal family that pre-exists it to a model in which family law provides a legal framework for the recognition and protection of the actual care relationships that people form.

Law 5 — revision — is the law that most directly governs the family law reform project. The revision required is not incremental adjustment at the margins of an otherwise functional system; it is a fundamental reconsideration of the social unit around which the system is organized. That reconsideration is happening, in fragments, across the legal system and the policy landscape. The question is whether it will cohere into a genuine revision of the framework or whether it will remain a collection of exceptions and workarounds that leave the nuclear-family default in place while providing limited protection for the social arrangements that the default excludes.