A Causby Worth Fighting For: The Supreme Court Case That May Shape the Future of Drone Airspace

United States v. Causby Still Reverberates Today

Long before drones, Amazon Prime Air, or low-altitude delivery networks entered the national conversation, the United States Supreme Court was already grappling with an important question: how much control does a property owner have over the airspace above their land? That question led to one of the most important aviation and property rights cases in American history: United States v. Causby (1946). Airplanes were a relatively new technology, being a product of the 20th Century, and as such they found themselves at the center of long-established property rights laws.

The case began on a chicken farm outside Greensboro, North Carolina owned by Thomas Lee Causby. During World War II, military activity around Greensboro expanded significantly, including operations at a nearby airport located less than a mile from Causby’s property. Large military aircraft frequently passed directly over the farm while approaching the runway—sometimes as low as 83 feet above the ground. For perspective, that was only about 18 feet above the tops of Causby’s trees. The consequences for the farm were severe. The noise and vibrations terrified the chickens, causing more than 150 of them to die after flying into walls and structures in panic. The constant low flights also disrupted the family’s sleep and daily life to such a degree that Causby was eventually forced to abandon the business altogether.

A Strong Argument for Serious Trespass

At the heart of the dispute was an ancient principle of property law sometimes described by the Latin phrase cujus est solum, ejus est usque ad coelum—roughly meaning that whoever owns the soil also owns upward “to the heavens.” Traditionally, land ownership was understood to include not only the surface and subsurface, but also the airspace directly above the property. And much like drones are doing today-- the introduction of aircraft into established property rights doctrine caused the laws to be reexamined.

Causby sued the United States government, arguing that the military’s repeated low-altitude flights were a forced taking and effectively “took” the use and enjoyment of his property without just compensation, violating the Fifth Amendment of the Constitution. The Court of Claims agreed with him and awarded two thousand dollars compensation in 1946, finding that the government’s use of the low airspace above the property had amounted to a taking.

The United States Appeals the Case to the Supreme Court

The government argued that under the Air Commerce Act of 1926, the United States possessed complete sovereignty over navigable airspace and that aviation depended upon a public right of transit through those skies. Congress had declared navigable airspace to be part of the public domain—a sort of aerial highway. The government further argued that because no aircraft physically touched the property, no trespass or taking had occurred.

But the Supreme Court ultimately sided with Causby in a 5–2 decision authored by Justice William O. Douglas. Importantly, the Court rejected the ancient idea that property ownership extends infinitely upward into the sky, stating that such a doctrine “has no place in the modern world.” At the same time, however, the Court also recognized that property owners still retain important rights in the “immediate reaches” of the airspace above their land.

The Court held that flights which are “so low and so frequent as to be a direct and immediate interference with the enjoyment and use of the land” can amount to a compensable taking under the Fifth Amendment. In other words, aircraft do not need to physically touch the ground to interfere with private property rights. If flights effectively skim the land and substantially disrupt its normal use and enjoyment, compensation may be required.

Which Brings Us to the Modern Era

What the Court did not do was define a precise altitude separating public airspace from privately protected airspace. That ambiguity has remained unresolved for decades-- and hence, poses a problem today when dealing with drones. Different aircraft operate differently, and some—such as helicopters, ultralights, balloons, and now drones—often fly far lower than traditional commercial aviation.

However, the Supreme Court did essentially establish two ideas simultaneously:

• Navigable airspace belongs to the public and is subject to federal authority;

• Property owners still possess enforceable rights in low-altitude airspace closely connected to the practical use and enjoyment of their land.

Commercial drones are increasingly operating in exactly the type of low-altitude environment that Causby addressed. Unlike passenger aircraft cruising thousands of feet overhead, drones may routinely operate just above rooftops, neighborhoods, farms, and backyards. They may also operate repeatedly over the same properties day after day as part of delivery networks or automated flight corridors.

This, of course, raises the difficult legal questions that the Supreme Court never fully answered in 1946: How low is too low? How frequent is too frequent? At what point does commercial drone activity become a direct interference with private property rights? The reality of drones today demands these questions have an answer.

Another Causby Is Coming...

It is increasingly likely that another Causby-like case will eventually reach the United States Supreme Court. Unlike the occasional military bombers that once rattled a few rural poultry farms in the 1940s, modern drones are now beginning to operate routinely in Extreme Low-altitude Airspace and in far greater numbers. As this extreme low-altitude drone traffic expands into everyday residential life, conflicts involving noise, privacy, safety, trespass, and property rights are almost certain to intensify.

Sites like SkyEasement.com exist in part to help document these growing disputes and facilitate the broader legal conversations and future litigation that may ultimately shape the next generation of American airspace law. It is our hope that the courts—and eventually Congress—will recognize the urgent need for clear and definitive low-altitude operating boundaries before the widespread deployment of commercial and eventually manned drones creates even greater disruption to the use and enjoyment of private property. The legal collision is coming. It is only a matter of time.