Parentage law is in the midst of rebalancing. Reformers urge states to define parenthood by caregiving rather than biology or marriage, arguing the law can better protect children’s well-being by offering parental rights to whoever functions as parents in the child’s daily life. Critics respond that these functional parent laws risk destabilizing children’s relationships with their legal parents. Much of this debate comes down to empirical questions: who raises functional parent claims and in what family contexts?
The most influential attempt to answer these empirical questions is a recent study by Courtney Joslin and Douglas NeJaime that coded every “functional parent” decision in Westlaw from 1980 through 2021. Joslin and NeJaime conclude that functional parent laws likely increase children’s family stability because the “overwhelming majority” of functional parents are primary caregivers and because legal parents are “routinely” not raising the child at the time of litigation. These two headlines have quickly become the empirical foundation for arguments in favor of expanding functional parentage.
Unfortunately, the headline findings are not a reliable guide for legal reform because functional parenthood law is not one thing. The findings accurately describe the distribution of cases across the dataset, but disaggregating the dataset reveals that caregiving roles and family structures vary substantially by state, doctrine, and time, often in ways that track underlying differences in doctrine and procedure. States tailored functional parent doctrines to distinct family problems, and those design choices shaped which cases appear in appellate courts. The pooled cases do not reflect a single, stable phenomenon and do not support general inferences about functional parenthood as a unified category.