A state’s jurisdiction once went from the depths of Hell to the heights of Heaven. Airplanes challenged this tradition, and satellites ended it. Since then, the upper limit of a state’s sovereignty has been long debated. Today, there is a distinction between airspace—where a state is sovereign—and outer space—which is res communis. Despite the distinction, there is no legal barrier delineating where air law ends and space law begins.
Although some states have called for a definition of where outer space begins, the United States is ambivalent on setting that border. As the US Delegate made clear to COPUOS, the US sees no practical reason to set a barrier. Because it sees no practical need for an air-space border, the US was concerned that making an arbitrary decision that would—as technology advances—become unworkable.
While it is true that air law and space law have worked well in their independent spheres, advancements in technology may force a decision as space becomes more accessible and more frequently used. Although the technology argument has been used since at least 1975 as an excuse to hold off on making a decision, the point may soon arrive where this distinction matters. Scholars developed two schools of thought to delineate a boundary.
Spatialist v. Functionalist
The “spatialist” approach sets the boundary for where outer space begins. Anything above the line is in outer space; anything below is in air space. Basing this delineation on natural phenomena is difficult because there is no rigid barrier between the atmosphere and outer space. The atmosphere does not simply just end and give way to the vacuum of outer space. Indeed, basing the air-space barrier on any atmospheric (when the atmosphere no longer protects against ultra-violet radiation or cosmic rays), chemical (when liquids evaporate), physiological (when there is no oxygen in the atmosphere), or aeronautical (when air is no longer dense enough to support lift or when air resistance is negligible) definition would not provide certainty. All of these points depend on properties of the atmosphere, which depends on myriad fluctuating variables.
If a spatialist approach is adopted, the boundary should be set at an arbitrary altitude. Unlike the aforementioned barriers, there would be no ambiguity or variability in the limit. This approach also has the benefit of state practice to lend it credence. However, despite several states have set an altitude limit in their domestic space legislation, there is no consensus about what that altitude should be. Over the years, however, states—following the emerging scientific consensus—are converging on an altitude of between 100 and 110 kilometers above sea level.
The “functionalist” approach disregards physical characteristics of a barrier in favor of basing the distinction on the space object’s purpose. It recognizes that air law and space law were designed with certain activities in mind and applies that law to the activity, regardless of where that activity takes place. In effect, it applies space law to space activities, such as satellite launches, and air law to aviation activities. The problem with this regime, however, is that some activities—such as suborbital flights—can be characterized as both an air and space activity.
Does This Distinction Even Matter?
Not yet. In the vast majority of cases it is clear which legal regime applies. However, Virgin Galactic’s successful test of its suborbital spacecraft on April 29 (and let’s not forget the other companies nipping at Virgin’s heels) means that this distinction will matter soon. Specifically, Virgin’s plan is to launch its customers 110 kilometers above sea level. Yet, the most current suborbital flight plans take off from and return to the same site. But future suborbital flights are intended to be a rapid means of transportation.
Ultimately, the functionalist approach provides the most effective and practical regime. This approach is commendable because it treats like subjects alike: suborbital flights, which are more analogous to civil aviation than to traditional spaceflight activities, are governed by air law and “traditional” spaceflight activities use the space law regime. For suborbital spaceflights, this makes particular sense because, like civil aviation, it is a commercial carrier conveying paying passengers from departure to destination. Although suborbital activities reach an altitude that would likely qualify as outer space under the spatialist approach, suborbital flights do not share many qualities of a traditional space activities. Air law has several decades of experience on space law at resolving liability, regulating transit, and protecting passengers. Why not let it do what it does best?