This paper studies the impact of the regime shift from maternal preference to joint custody, in custody
dispute adjudication during the 1980s using the one percent Integrated Public Use Microsample Series (IPUMS)
of the decennial Census for the decades from 1970 to 1990. We focused on children between the ages of 15
to 18, who were living with a single divorced or separated parent and children of intact families. Educational
attainment was used to quantify child outcomes. Using cross state and year variation in the timing of adoption
of those laws, we found strong evidence that the children of these single parent households, living in states which
adopted joint custody, had a higher probability of high school graduation by age 18. On the other hand, we
found that children from intact families su§ered a decrease in probability of high school graduation by age 18.
This suggests that the law has important unintended negative e§ects that had been thus far neglected. The
result on children from intact families was replicated using the IPUMS Current Population Survey Sample, and
results concur with the Öndings from the census dataset. The results were also replicated when we relax the
distributional assumption using stochastic dominance techniques