Medical Marijuana Laws Linked to Fewer Foster-Care Entries Citing Parental Drug Abuse
A 2025 study found that medical marijuana legalization was associated with fewer foster-care entries involving parental drug abuse—but not with a clear reduction in foster-care removals overall.
Published in the Review of Economics of the Household, the study by Cullen T. Wallace, Chris D. Clark and Brent Evans examined whether changes in marijuana policy were followed by changes in child-welfare cases attributed to parental drug misuse. The researchers analyzed approximately 3.4 million foster-care entries recorded between 2007 and 2019.
Using several difference-in-differences methods, the researchers compared states that adopted medical or recreational marijuana laws with states that had not done so. Their models accounted for state-level economic conditions, including unemployment and per-capita income, as well as characteristics of children entering care and other reported removal reasons.
The analysis found no statistically significant change in foster-care entries related to parental drug abuse after states legalized recreational marijuana. Medical marijuana legalization, however, was followed by a decline in those entries. The estimated reduction was about 20 percent in the second year after implementation and roughly 30 percent in the third and fourth years.
The researchers attributed the medical-marijuana result to states with relatively strict limits on tetrahydrocannabinol, or THC, the main psychoactive compound in cannabis. They did not find convincing evidence that medical marijuana laws reduced the total number of children removed from their homes. In other words, the findings concern the reason recorded for foster-care entry, not necessarily the overall number of removals.
That distinction is important because foster-care records can list multiple conditions associated with a child’s removal, and the way agencies identify and record parental substance use can vary by state. Federal data compiled by the National Center on Substance Abuse and Child Welfare show that parental alcohol or other drug abuse is frequently identified as a condition associated with removal, while also noting that reporting practices differ across jurisdictions.
The study cannot establish exactly why the decline occurred. One possibility is that child-welfare officials became less likely to treat marijuana use itself as evidence of parental drug misuse after medical use became legal. Another is that legalization changed patterns of substance use or made regulated medical access more common. These explanations remain hypotheses rather than conclusions directly tested by the study.
The findings also do not mean that medical marijuana is harmless or that legalization prevents child maltreatment. The researchers focused on administrative foster-care records and policy changes, not on the safety of cannabis use in individual households. Nor did the analysis show that legalization reduced foster-care entry for every reason.
The results differ from those reported in a separate 2022 study, “Recreational marijuana legalization and admission to the foster-care system” by John Gardner and Bright Osei. That paper estimated that recreational legalization was associated with at least a 10 percent decrease in foster-care placements, including entries involving parental drug or alcohol abuse, physical abuse, neglect and parental incarceration. Differences in study periods, methods and the states covered may help explain the contrasting results.
Taken together, the research suggests that marijuana policy may affect how child-welfare agencies classify and respond to substance-related cases, but it does not provide a simple answer about whether legalization improves child safety. More research is needed to separate changes in official reporting and enforcement from genuine changes in family conditions.
