For hundreds of years, common law adhered to the ancient Latin doctrine 'Cuius est solum, eius est usque ad coelum et ad inferos'—whoever owns the soil, it is theirs up to heaven and down to hell. This worked remarkably well when the highest human achievement was a multi-story building. However, the invention of aviation shattered this legal harmony.
The breaking point arrived in 1946 with the Supreme Court case United States v. Causby. Thomas Lee Causby was a North Carolina farmer whose chicken farm sat directly in the glide path of a military airport during World War II.
Military bombers flew as low as 83 feet directly over his house and barn. The terrifying noise and glare caused Causby's chickens to panic, fly into walls, and die by the dozens, effectively destroying his business. Causby sued the federal government, claiming a physical taking of his property under the Fifth Amendment.
The government argued that the airspace was a public highway. Writing for the majority, Justice William O. Douglas recognized that the 'ad coelum' doctrine had no place in the modern world, stating that executing it literally would clog air travel with endless trespass lawsuits.
However, the Court ruled that a landowner owns at least as much of the space above the ground as they can occupy or use in connection with the land. Because the low-altitude flights directly interfered with Causby's use and enjoyment of his farm, the Court ruled it was an unconstitutional taking, effectively setting the legal boundary where private property ends and public airspace begins.