Accessory Dwelling Units and the Preemption of Land Use Regulation

Christopher Wielga
University of Missouri

The Standard State Zoning Enabling Act of 1922 encouraged states to delegate land use regulation to local governments via zoning, a task that became a core part of local government. One hundred years later, with increasing criticism of local land use regulation, state governments are rethinking local control over land use, including limiting the zoning powers of local governments. An example of this is state preemption of Accessory Dwelling Unit (ADU) regulations. This article reviews the preemptions from the nine states that have implemented them, and describes how these policies have evolved over time, showing that additional states have adopted these policies and that the preemptions have been strengthened. It also develops a framework of stronger versus weaker policies, with stronger policies more completely preempting local governments, applying to more jurisdictions, and having fewer exemptions. Despite the overall strengthening of state ADU preemptions, the preemptions often remain weak. State governments may find it difficult to effectively preempt local governments through continued legislation, and more effective preemptive regulatory power may be better placed in the hands of state agencies.