Originally Posted by
DrLeeCRogers
Most airports aren't actually Federal property. They are city, county, or port authority property. If you get arrested at the airport, you're arrested by the local police, not the FBI. Yes there are a mixture of Federal, State, and local laws that govern airports and travel, but the local government can enact laws more strict than the Federal laws. Hence, some airports don't allow smoking (by local law, even though there is no Federal law to ban smoking indoors). So the local municipality could make it illegal to operate a device to irradiate humans without a license, or something similar.
Your smoking example is flawed because the
lack of a law isn't a "conflict". Whether the airport is Federal property or not isn't relevant either.
However, I think the supremacy issue is a bit more complex than
Lobbyist is acknowleging. The classic aviation-related example is that localities can't pass laws that purport to regulate flight paths because that conflicts with the Federal power to regulate aviation. But I think they
can issue time curfews and completely
close an airport, if they so choose. So it's not absolute.
In the screening arena, there's no question that the legislation creating the TSA is sufficient to make unenforcable any local laws that would affect screening, but
only those part of screening that were "valid". If a court were to hold that the screening was unconstitutional, then the law is not "valid". For example, if a jurisdiction were to make operating an AIT a felony and charged a TSO under that statute and the court ruled as part of that prosecution that the AIT was a unconstitutional search, that prosecution may well succeed. IANAL, of course.