Adult adoption is one of the stranger corners of family law, strange because it is both ancient and almost entirely invisible in contemporary public discourse. Most people, when they encounter the phrase, assume it refers to cases where a stepparent formally adopts a stepchild who has aged out of minor status — a technical clean-up of an existing family relationship. That happens, and it accounts for much of the caseload. But adult adoption has a second use that the law has permitted for centuries and that receives almost no attention: two adults with no prior family relationship, no sexual partnership, no financial entanglement, can choose each other as legal family. One becomes the parent; one becomes the child. The law does not inquire into why.
In most U.S. states, adult adoption requires only that both parties consent and that a court find the adoption in the interests of the adoptee. There is no home study, no waiting period, no requirement of prior relationship, no prohibition on the adoptee being older than the adopting parent. A fifty-year-old can adopt a sixty-year-old. Two friends of the same age can, in many jurisdictions, adopt each other through sequential petitions. The legal effect is real: the adopted adult gains inheritance rights in the adoptive family, the right to be treated as a child of the adoptive parent for intestate succession purposes, access to the adoptive family's benefits where those extend to children, and a formal next-of-kin status that gives them standing in medical and legal contexts.
This mechanism has been used by same-sex couples who could not marry, by elderly people seeking to secure their caregivers' legal standing, by chosen family networks seeking formal legal recognition, by wealthy individuals structuring succession planning, and by people in cultures that practice formalized intergenerational friendship as a social institution. It has also been abused: a cluster of cases in the early 2010s involved adult adoption to obtain legal standing in personal injury suits or to circumvent inheritance limitations, and some jurisdictions responded by tightening their standards.
The abuse cases produced headlines; the legitimate cases — the lifelong friend adopted as a sibling by a dying person's surviving family member, the elderly woman who adopted the neighbor who had cared for her for fifteen years — produced almost none. The law as written permits a remarkably broad range of chosen-family formations. The friction is social, not legal: most people do not know this option exists, and those who do know it often find the parent-child frame uncomfortable when the relationship they are trying to protect is between equals.
That discomfort is worth sitting with, because it illuminates the deeper problem. The law does not have a category for equals choosing each other as legal family. The only formal kinship instruments it offers are marriage (between adults in a romantic relationship) and adoption (between a parent and a child). Both are hierarchical in design, one explicitly and one structurally. The friendship relationship — chosen, symmetrical, horizontal, built on mutual recognition rather than care obligation — has no legal analog that directly fits it. Adult adoption is a workaround, not a solution. It works, and it is better than nothing, but it asks people to describe a horizontal relationship in vertical terms to get the legal protection they need.
The planning challenge this poses at the collective level is real. Legal systems are built on categories, and the categories available for intimate relationships are inadequate to the actual variety of human bonding. Extending the reach of adult adoption law — lowering barriers, standardizing procedure, making it available in every jurisdiction — is the proximate reform. The more fundamental reform is creating a non-hierarchical, non-marital legal kinship instrument that does not require anyone to call a peer their child. Until that exists, adult adoption will serve as the closest available fit, used by people who know it exists and are willing to tolerate the awkward framing. That population is small and concentrated among people with legal literacy or the resources to obtain it. The people who most need formal kinship protection are least likely to know this tool exists.