From Wikipedia:
Cuius est solum, eius est usque ad coelum et ad inferos (Latin for whoever owns the soil, it is theirs up to Heaven and down to Hell) is a principle of property law which can be traced back to 1766, when William Blackstone boldly proclaimed the doctrine in his treatise Commentaries on the Laws of England. It was not a principle of Roman law, despite the Latin phrasing of the maxim, nor was the theory recognized in early common law. Rather, it is best viewed as hyperbole invented by Blackstone, without any prior foundation in English law. By the end of the 19th century, frequent repetition had transformed Blackstone's naked assertion into a supposed rule of American law.[1]Or as I like to put it, the owner of real property owns it "half way to China and all the way to Heaven." Why only half-way to China? Because the Chinese landowner owns his land half way to America. No? You got to think globally, Sir William!
As the name describes, the principle is that a person who owns a particular piece of land owns everything above and below it as well. Consequently, the owner could prosecute trespass against people who violated the border but never actually touched the soil. As with any other property rights, the owner can sell or lease it to others, or it may be taken or regulated by the state.
For example, suppose three people owned neighboring plots of land. The owners of the plots on the ends want to build a bridge over the center plot connecting their two properties. Even though the bridge would never touch the soil of the owner in the middle, the principle of cuius est solum would allow the middle owner to stop its construction or demand payment for the right to do so.
By the same principle, a person who wants to mine under somebody's land would have to get permission from the owner to do so, even if the mine entrance was on neighboring land.
