Part of it began during WWII. Thomas Causby (and his flock of chickens) had a parcel of land about a half mile from Lindley Field in Greensboro, North Carolina. The United States government, via what was then the Department of the Army, used Lindley Field for training bomber and fighter pilots. And they used it a lot. So much in fact, that over 150 of Mr. Causby’s chickens died due to the noise and vibrations from the constant takeoffs and landings. The location of Mr. Causby’s property placed the landing and departing aircraft approximately 85 feet over the farm (and only 20 feet above the farm’s highest object). Mr. Causby filed an inverse condemnation lawsuit against the government for damages, claiming that the airport’s activity had cost him his business and that the United States had “taken” without compensation his rightful property from him. He claimed that this was a clear violation of the Fifth Amendment of the Constitution.


Wait. The Fifth Amendment? The one that protects us from answering questions that may incriminate us in a criminal matter? That Fifth Amendment?


Yes. The Fifth Amendment was created to provide citizens with certain rights and protections, such as protection from self- incrimination, the right to due process, the right to a grand jury (for felony indictment), the protection from double jeopardy, and the one that interested Causby – the right to compensation if the government “takes” private property. As the founding father James Madison drafted it, “nor shall private property be taken for public use, without just compensation.” This was Causby’s problem with the government. He wanted restitution for what he had lost due to the government’s actions.


Causby’s case was heard before the Court of Claims, a U.S. federal court that adjudicated monetary claims against the United States (This court was abolished in 1982 and all trial cases were moved to the United States Court of Federal Claims). The court held that the United States had indeed “taken” Causby’s property by allowing aircraft to fly below 300 feet over the farm, and that Causby owned more than the actual real estate. Known as a common law “ad coelum” doctrine – “whoever’s is the soil, it is theirs all the way to heaven and all the way to hell” - the Court of Claims held that all the air above (and by interpretation, all the ground below) belonged to Causby. The court ruled that the United States had violated that ownership, so Causby was due “just compensation.”


The United States appealed to the Supreme Court. In a 7-2 ruling, that court held that Causby did not own any of the air above his property. The high court held that the ad coelum doctrine “has no place in the modern world.” However, it also held that the flights over Causby’s farm were conducted outside of “navigable airspace” and therefore his property was indeed “taken” because it was useless for its intent (raising chickens), and he was probably due some sort of compensation. The court remanded the case back to the Court of Claims. That court’s job then became one of determining exactly what kind of damage was done and how much that equaled in dollars.


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It’s important to recognize that the two dissenting justices agreed that Causby deserved compensation, but they thought compensation should have been determined at the state level instead of the federal level. That, of course, could not happen as the defendant in the case was the federal government, and the damages had to do with flights outside of navigable airspace, which was (and still is) regulated by the federal government.


Causby was eventually compensated, but only for the loss of his occupancy of the physical real estate and not for the loss of his chickens. (He could no longer be a chicken farmer and therefore his property suffered dwindling value.) His suit against the United States, and his ultimate victory in proving “taking” without physically touching the property (by aircraft flying overhead), is now known as “avigation easements.” Around the time of the Causby case, Congress legislated that the United States “is hereby declared to possess and exercise complete and exclusive national sovereignty in the airspace above the United States.” Because of the Causby case, Congress also changed navigable airspace to include “airspace needed to ensure safety in the takeoff and landing of aircraft.”


The importance of this case in reference to the National Airspace System are the words “navigable airspace.” Causby institutionalized the need for more definition and reminded us that navigable airspace is owned by the United States because of the commerce clause of the Constitution, which gives ownership of navigable waterways and public highways (and public airways) to the federal government. The federal government ended up paying Causby because it owned what it took from Causby. The frequent low-level flights were the “direct and immediate cause.”


So where did this airspace start? What was considered “minimum altitudes?” And were those altitudes safe enough? The early answers to those questions were placed into law via the Air Commerce Act in 1926 and the Civil Aeronautics Act (CAA) in 1938, but up until Causby, nobody ever really discussed this outside of the CAA regulations. Those regulations established that navigable airspace is the airspace above the minimum safe altitudes of flight (prescribed by regulations issued by the Civil Aeronautics Board), but does not include airspace below the minimum safe altitudes necessary for takeoff and landing. Hence, the award to Causby. A 500-foot minimum altitude was established, except for takeoff and landing.


So now we had, in addition to the applicable acts from 1926 and 1938, a true case-law definition of “navigable airspace” and “minimum safe altitudes.” But why is the “taking clause” ruling of Causby so important to today’s National Airspace System? Because it established the need for pilots to recognize and comply with airspace rules. Violations will give cause to a lawsuit claim that “taking” occurred. As the years went by, three more cases would further define “taking:” Griggs v. Allegheny County (402 Pa. 411, 168 A.2d 123 (Pa. 1961)), Branning v. United States (654 F.2d 88 (Fed. Cir. 1981)), and Brown v. U.S., 73 F.3d 1100 (Fed. Cir. 1996).


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