Doug Hess, Michael Hanmer, and David Nickerson have written this article for Public Administration Review. Here is the abstract:

Can state officials increase local officials’ compliance with an important federal civil rights law with subtle interventions? The National Voter Registration Act of 1993 (NVRA) requires voter registration services at certain government agencies, but many counties fail to comply with the act. Working with officials in two states, the authors conducted field experiments to determine whether two methods commonly used by state officials increase compliance with the NVRA. Findings show that although the effects of the methods on output were sizable relative to recent performance, agency performance remained poor overall, with many offices continuing their history of registering no voters. The authors also discovered that gains in performance were largest for the offices that had performed best in the past. These findings suggest that while subtle interventions by state officials can produce increased compliance, stronger tactics may be needed to secure implementation of this federal law by local government agents.