A profound transformation has occurred in the legal relationships between children born outside marriage and their noncustodial parents over the past two decades.  For most nonmarital children, their father voluntarily signs an acknowledgement of paternity in the hospital, and this becomes legal if not contested.  This legal paternity means that a child support order could then be established, just as it could for cases in which the father did not acknowledge paternity in the hospital but was found to be the father by a court.  When a child support order is entered for nonmarital children, an assignment of decision-making power can also be made to either the mother, the father, or to both parents jointly.  This right and obligation to make important decisions for the child is called legal custody, a concept different from but often jointly determined with physical custody, which specifies the parent the child physically lives with.

Over the last thirty years, many states have changed their policies to encourage joint legal custody in which the parents share decision-making power.  Wisconsin changed its laws in 1999, partly hoping that this would encourage greater father involvement.  However, little is known about the effects of this policy.  In this paper, I document trends in legal custody before and after the policy change: data from court records in Wisconsin show that joint legal custody has risen dramatically in the last twenty years, from 10 percent of nonmarital cases in the early 1990s to 70 percent in the late 2000s.  The predominant living arrangement for nonmarital cases remains physical custody solely with the mother, although there have also been changes in living arrangements for these children, with the percentage who live with both parents increasing from fewer than 2 percent to 8-10 percent over this period.  This paper also aims to explain the upward trends in joint legal custody for nonmarital cases, using the same data from Wisconsin Court Records from 1992 through 2007.  I explore the extent to which the shift in custody can be explained by changes in child support and child custody policy or demographic and economic characteristics of parents.  Preliminary analyses suggest that the trend is related to changes in the policy surrounding legal custody, and to some economic and demographic characteristics of the parents, including their income and their prior fertility patterns.