Good Fences? Good Luck

Released in the Cato Institute’s Regulation magazine, IJ’s study “Good Fences? Good Luck” is the first study to put a number on the amount of private property vulnerable to warrantless searches by federal agents thanks to a legal precedent known as the “open fields doctrine.” It finds that nearly 96% of all private land in the country—about 1.2 billion acres—is essentially open to federal government trespass. 

Created by the U.S. Supreme Court in 1924, the doctrine holds that the Fourth Amendment’s ban on warrantless searches do not apply to so-called open fields, meaning any land not immediately abutting a home. Today, federal agents rely on the doctrine to invade private land for activities like covert surveillance, placing cameras, and taking cameras. IJ’s study uses spatial analysis techniques to quantify the number of acres in each state that are privately owned and not near a home or building. The study made generous assumptions about what areas would be protected by the Fourth Amendment, treating all structures and a 100-foot buffer around those structures as protected. The results show the massive scope of the open fields doctrine.

States cannot provide less protection to property owners than the federal constitution and precedents, but they can provide more. Indeed, seven states have rejected the open fields doctrine under their own constitutions. IJ’s study compares the amount of private land in those states eligible for protection under the open fields doctrine versus the state constitution and found a difference of more than 160 million acres. 

Until the Supreme Court overturns the open fields doctrine or Congress legislates it away, the doctrine is here to stay. But state courts and legislatures have the power to protect millions of acres of private land from abuse under state law. As IJ’s study shows, this can make a huge difference when it comes to preventing warrantless searches by state officials.

Windham, J., & Warren, D. (2024). Good fences? Good luck. Regulation, 47(1), 10–14.

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