"Legal" drugs--or not?

[bcubed]

I originally was interested in this as it relates to Salvia d., but it's applicable to other drugs as well.

Obviously, some things are legal federally, but not in a given state (such as S.d. in certain U.S. states) and vice versa (specifically "medical marijuana", which is B.S., because the feds are supposed to grant power to the states as a default, only excersizing legislative power when state oversight is insufficient.)

Recently, SWIM tried and failed to purcase S.d. in a city located in a state where S.d. is legal and was told, "We had to stop selling it--city ordinance."

So, could SWIM get in trouble for a drug, legal in a given state, that has been outlawed by a county/city/township/etc? I've no idea how this works: if SWIM drove from one end of a state to the other, could he be legal in seven of the counties he passes through and illegal in five?

Extra Credit question: what about drug laws in int'l waters? Legal to do drugs in a private boat/private plane/cruise ship/commercial flight?

More Ex Cred: Let's throw in a number of perplexing legal issues. This would apply to drugs legal in one state, and illegal in another (this is a U.S. problem, though it might apply to Provinces, etc in other countries, though most countries are more "federal," it seems than the U.S.) The only drugs that come to mind are S.d. and Amantia muscaria, though I'm sure there's others.

1a. SWIM wants to fly from CA (legal S.d.) to Philly, PA (same). Due to a thunderstorm, however, the flight deviates south and overflies Deleware (illegal) airspace. Is SWIM in trouble?
1b. Turns out Philly is fogged in and flight diverts to Wilmington, Deleware. Upon landing, SWIM is accosted and charged w/ posession. Since there is no "criminal intent," is this equivalent to someone stashing, say, pot in SWIM's bag unawares?

2. SWISWIM (think about it) elects to openly start a mail-order business, based in Philly and selling in Wilmington. This is interstate commerce (federal), using the US Postal Service (federal gov't). DE might put out a warrant, but SWIM can't be extradited (?) because the offense isn't illegal both in where he resides AND where he sells [I know this is the case internationally, but unsure on the state level.] As long as SWISWIM NEVER sets foot in DE, is he golden?

Sorry about all the theoretical questions, but SWIM travels a lot and he'd like to know. Trust me, the last Q is ENTIRELY theoretical, not least because SWIM visits DE on occasion.