Hate to jump into the middle of a thread, but largely they are state laws, almost every state passed a law like this post 9/11. That's why they don't need a federal marshal to arrest you if you really went off the rails.

Strangely enough, these apply to ground crew or anybody who has responsibility for the safety of the airline, even as a check on each other. I used to keep a copy of our state's law in the pilot lounge because we had too many incidents of stressed out cargo pilots trying to cut corners.

Also, gotta say, the converse is true as well, just because you express skepticism about something doesn't mean it's not true.