(Coauthored with John F. Duffy)
As discussed in a prior post, the core argument in our recently published article "Major Technological Questions" is that courts and agencies should hesitate to interpret ambiguous pre-existing legal authority as resolving legal questions newly raised by major technological developments. As we noted in that earlier post, we draw an explicit analogy to the modern major questions doctrine. Nonetheless, major technological questions differ from the large scale economic and social issues that currently trigger the major questions doctrine. Furthermore, major technological questions have applications not only in judicial interpretations of old statutes, but also in judicial application of pre-existing common law. In this post, we provide an excellent historical example of how courts should approach major technological questions in the application of pre-existing common law and in the formulation of new common law.
Our example involves a major technological question arising during the early legal history of powered flight. (Appropriately enough, one of us was writing and editing this post in a comfy chair 36,000 feet over the North Atlantic—something that would have been nearly unimaginable a century ago.) When the Wright brothers made their historic flight in 1903, they avoided legal complications because their tests occurred on unowned beaches or personally owned land. But as aviation developed, a key legal issue soon emerged: whether airplanes flying over private land constituted trespass.
At the center of this issue was the old common law maxim: "Cujus est solum, ejus est usque ad cœlum et ad infernos"—translated as, "To whomsoever the soil belongs, he owns also to the sky and to the depths." This phrase, originating from Roman legal traditions and later embedded into English common law by preeminent legal authorities like Lord Coke and William Blackstone, seemed to suggest that landowners had rights extending vertically into the air above their land.
However, the maxim, while often cited, is riddled with ambiguities, especially when applied to the context of flight. Blackstone's Commentaries on the Laws of England provides the best source for understanding those ambiguities, and they fall into three major categories.
- What's the Nature of Property Rights in Airspace?
Blackstone asserts that land legally extends both upward and downward, seemingly supporting the view that landowners control the space above their land. Yet, elsewhere, he distinguishes between tangible property (like land and buildings) and things like air and water, which he describes as common to all and only capable of "usufructuary" ownership—meaning that people can own and use them only while they remain in possession.
Thus, while landowners have some rights in the air above their property, these rights may be temporary and use-based, not absolute. The implication would be that surface ownership may not entail a right to exclude all overflights, particularly if the flights don't interfere with the use and enjoyment of the land and the physical structures attached to the land (like a building).
- How High is the Sky?
The Latin phrase "ad cœlum" implies ownership "to the sky," but not necessary into or through it. The phrase thus raises the question of where exactly the sky begins or ends. Blackstone does not define this limit, but he does refer to land rights as having "indefinite" rather than "infinite" extent. Historically, the "sky" was conceptualized as relatively low, particularly before modern structures and technologies like skyscrapers and airplanes became common. Even in the 19th century, tall buildings—reaching only a few hundred feet—quickly became known as "skyscrapers," and many sources referred to such tall buildings as extending "into the sky." Such references suggest that, prior to the modern era, people viewed the "sky" as beginning at a relatively low altitude. If this interpretation holds, then aircraft flying at higher altitudes might not infringe on landowners' property rights even under the "ad coelem" maxim because property rights reached only "to the sky."
- Do Property Rights Include Absolute Exclusionary Rights?
Another issue lies in the distinction between owning property and having an absolute right to exclude others from it. Blackstone himself notes in another volume that not all trespasses are unlawful; some may be justifiable, especially when they serve the public good. For example, hunting certain dangerous or nuisance animals on private land could be allowed if such hunting benefits the broader public. This idea—that some intrusions are acceptable if they are, in Blackstone's words, "profitable to the public"—could extend to airplane overflights. While flying over someone's land is not the same as chasing a fox through it, both could be justified if they serve a greater good, such as efficient transportation.
Implications for New Technology
Each of those ambiguities in traditional legal doctrine demonstrates why it is risky to treat past law as dispositive when dealing with new technologies. The maxim that a landowner owns everything "to the sky" or "to the heavens" was never precise or universally applicable, and its application to aviation—let alone to emerging technologies like drones, satellites, or space tourism—is highly uncertain.
The broader point is that the legal system must be forward-looking when addressing the implications of new technology. Courts should recognize that new inventions will often not fit neatly into preexisting legal categories. In fact, attempting to force new developments into old frameworks can result in stifling innovation or creating legal instability.
Ultimately, that is what the courts did with the trespass claims made during the early era of powered flight. They did not try to look at the pre-existing materials and ask, for example, what Blackstone would have thought if he had thought about the possibility of powered flight. They also did not try to parse the exact words of the legal maxim and then try to decide where a Roman or early English lawyer would view the sky as beginning.
Instead, the courts viewed the prior legal materials as simply not addressing the issue whether overflights were trespasses. The courts then, as common law courts, were free to adopt a legal rule based on policies that were responsive to the new technology. The end result—that planes flying over private property at relatively high altitudes did not trespass on the underlying owner's property but that ones at low altitudes (such as under 500 feet)—was based on modern assessments of, and balancing of, the economic interests that flight presented. Importantly, that resolution left open the possibility of further development in the industry and prevented an ancient and ambiguous legal maxim from thwarting the development of a new technology that, while small then, was destined to grow into one of the world's vital industries.
