There are certain acts for which US law can/will prosecute US citizens who commit them abroad. If you travel abroad to sell classified secrets to another country, you will be prosecuted (espionage.) If you sexually abuse a child in another country, you will be prosecuted (Protect Act.) If you go abroad to join a terrorist group, you will be prosecuted. Etc. etc.
But at what point - if any - does the US government no longer have a right to control what a US citizen does overseas? If, let’s say, a US citizen were driving a car in Ireland and ran a red light, I think we would all say it’s excessively heavy-handed for the US to have a law making it illegal to run red lights in a foreign country - that would be tantamount to making the entire world US jurisdiction, or whatever the correct term would be.
Is there a point at which the Constitution, or precedent, or other law, says, “What happens abroad is abroad, and not our business, while what happens at home is at home?”
I can’t think of any Constitutional limit. The practical limit is that the federal government has enough on its plate before adding minor traffic violations committed overseas, so they’re generally limited to the Really Bad stuff: terrorism, child abuse, massive financial fraud.
Correct me if I’m wrong, but doesn’t some Asian country (South Korea, I think) forbid their citizens from gambling while overseas? And like, they’ll check your social media and shit at the airport when you come home, and if there are pictures of you in a casino, you’re busted. ISTR reading that somewhere?
I mention this only as an anecdotal discussion point, since it is not directly related to the OP’s question.
I was surprised to hear that, but it seems to be true: South Korea's Gambling Law. That blog post states, however, that prosecution of South Koreans for gambling abroad is usually “part of a more substantial allegation against the individual” - probably it’s a convenient go-to provision for authorities if they already target someone for other reasons.
I don’t think so. The Constitution doesn’t say much about what government can’t do. That’s why we ended up with a Bill of Rights.
Congress makes laws based on its enumerated powers. The portions of the Protect Act (to my IANAL eyes) you mention appear to be justified by the commerce clause. And your other two examples are treason, which is of course the only crime mentioned in the Constitution at all.
So if Congress passed a law saying “it’s illegal to run red lights in Ireland,” it would have to in some way justify that based on what the Constitution says it can do.
In the US House of Representatives a bill being submitted is to be accompanied by a Constitutional Authority Statement briefly explaining which Enumerated Power applies to this proposal. It does not have to be extremely granular about it, just good enough to point to what constitutional power would apply, to get the legislating process started.
I guess the point would be that selling US secrets anywhere would be a form of treason.
I seem to recall some discussion that the Protect act does not make it illegal to have sex with minors outside the USA - it simply made it illegal to travel with the intent to do so - i.e. to cross the US border. I vaguely recall some news article where they then made the “intent” provision somewhat vaguer, arguing in some recent case that it did not mean they had to prove you had the intent while departing the country, just that you travelled and eventually performed the act, which indicated that at some point you had intent. So basically lawyerly hand-waving.
However, they have the laws about piracy on the high seas being prosecutable in the USA. (Is that a treaty about Law of the Sea giving them authority which previously was common law?)
Similarly, isn’t there the assertion that murdering a US citizen anywhere in the world makes you subject to US jurisdiction?
Piracy is considered a crime against humanity (pirates are hostis humani generis, or enemies of mankind), and by general consensus, states can prosecute those crimes regardless of territorial jurisdiction. For example, the United Nations Convention on the Law of the Seas says you can prosecute your own citizens’ piracy or other peoples’ citizens’ piracy so long as there is a nexus to your own citizens .