Perry Metzger points out in an email to me (feel free to email your comments to me; spammers certainly do, and I already hate them; I'm not likely to hate you any more, so don't be shy) that there's legislation and there's legislation. I had written that legislation is an act of man and a law is a fact of nature. Perry's point is that legislation can work against a law, or legislation can work with a law.
Consider that nobody but nobody wants an airplane flying a hundred feet over their house. Not even the most crazed airplane fanatic wants that. Thus your property right includes the ability to control the use of the air above your house. And yet it's ridiculous to claim that that right to airspace extends up to orbital level, giving you the ability to control the flight of satellites you can't even see with the naked eye. Somewhere the law stops.
A society could establish the limit through court cases, allowing people who object to go head to head against people who have a need to use the airspace. That would result in a fairly arbitrary number. But why not pass legislation to decide this number? Whether the legislation chooses 500 or 600 feet is a fairly arbitrary number. However, by passing the law, it allows everyone to enjoy their property without having to establish the number by legal action.