The regular course of the flight was through Newark, though, right? So he would hold at least a little responsibility in knowing NJ laws as well as PA just in case his connecting flight was delayed/canceled, since that's a fairly common occurrance and it's usually something a lot of people, even if they don't plan for it, know could happen.

Well we don't know (from that article) why it took so long to post his bail. It could have been that he didn't have anyone who could readily bail him out and/or some other kind of something going on there. Keep in mind, he's from Utah, not NJ.

I would imagine he might have a stronger case against the airline, because they put the final destination for his luggage to be Newark, not Allentown like he had requested, and if the luggage had made it to the bus it would have remained checked, right?

The case heard by the Third Circuit (and which the Supreme Court said it would not hear) was not a criminal case, it was a civil case.

Yes, he was held for 10 days until he could post bail, but the state prosecutor later dismissed the charges. When that happened, the criminal case was over. No more criminal case.

After the criminal case was over, this guy sued the Ports Authority. He did not sue for malicious prosecution, wrongful arrest or something like that. He sued for violation of his rights under the Firearm Owners’ Protection Act. The courts said he couldn't sue for violation of his rights under FOPA because when he took his gun to the hotel, he removed himself from FOPA's protection. Whether that holding was correct, not his arrest and detention, was what the case in the Supreme Court was about.

Some of the comments in this thread are combining and confusing the earlier criminal proceeding and the civil case actually before the Court, as though the Third Circuit's holding in this case means that anyone traveling with a gun who finds himself rerouted has to be aware of the gun laws in all states or risk criminal prosecution. That's not what this case stands for at all; it stands for the proposition that you can't bring a civil action under FOPA if you didn't comply with the requirements of FOPA. The Third Circuit's suggestion that one go find a law enforcement officer at the airport and explain the situation is not a suggestion on how to avoid criminal prosecution (although following the suggestion may have that effect) -- it's a suggestion on how to stay within the protection of FOPA when one is rerouted like this. (And the whole point of FOPA, at least as it applies in this instance, is that as long you know what you're supposed to do under FOPA and do it, you don't have to worry about knowing the laws in every state where you might find yourself.)