a landowner retains complete domain over the lower altitudes above their property. The court noted that ad coelum "had no meaning in the modern world", while also holding that "if the landowner is to have full enjoyment of the land, he must have exclusive control of the immediate reaches of the enveloping atmosphere. Otherwise buildings could not be erected, trees could not be planted, and even fences could not be run" and "The fact that he does not occupy [the space] in a physical sense -- by the erection of buildings and the like -- is not material. As we have said, the flight of airplanes, which skim the surface but do not touch it, is as much an appropriation of the use of the land as a more conventional entry upon it." id 264 . On remand, the Court of Claims established the landowner's property extends upward to only 365 feet, but not above: see Causby v U.S. court of claims (1948). The "ad infernum" theory positing property ownership "to the center of the Earth" has also been eroded. A review of modern American jurisprudence demonstrates that the theory is more poetic hyperbole than binding law, and that broadly speaking, the deeper the disputed region, the less likely courts are to recognize that the surface owner holds subsurface title. Appraisal studies of subsurface projects such as subways, deep storm drainage tunnels, and particle colliders consistently conclude that such projects, built well below the area that the vast majority of surface property owners ever put to use, do not deprive the surface owners of any value. International law With the advent of space exploration, the upper limits to the "ad coelum" doctrine now include issues of national sovereignty. Strong arguments can be made for and against the altitude at which national sovereignty ceases and the rights of orbit or travel start. In particular, the making of national territorial claims in outer space and on celestial bodies has been specifically proscribed by the 1967 Outer Space Treaty, which was, , ultimately ratified by all space-faring nations. Article II of the treaty notes that "Outer space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation." The "ad coelum" doctrine - that property or sovereignty extends indefinable upward - is no longer accepted without limitations. This is not surprising