Are there any US laws that a US citizen MUST obey while traveling, even if those laws do not exist in the country he is traveling to?

Question

It goes without saying that the laws vary from country to country, and what is illegal in one country might be both legally permitted and culturally accepted in another.

For example, in the US the minimum age to legally consume alcohol is (generally) 21, but in many countries, the minimum age is 18 or lower. It is possible for a 19-year-old US citizen to travel to Chile, for instance, and consume alcohol legally according to the local laws.

I am curious, though, if a US citizen could potentially* be prosecuted upon returning home for "breaking US laws while on foreign soil".

Is that idea as absurd as it sounds, or are there US laws that US citizens MUST obey while they are traveling, even if no such laws exist (or are less strict) in the countries they are traveling to?

* Leaving aside the practical consideration of how anyone would ever find out what the traveler did during his trip; I'm more curious to know if there's a precedent.

Answer 1

I am curious, though, if a US citizen could potentially* be prosecuted upon returning home for "breaking US laws while on foreign soil".

Yes.

1. The U.S. maintains embargoes against several countries, the best known of which is Cuba. Many of these include travel restrictions. It is illegal, for example, for a U.S. person to use U.S. currency or a U.S. passport to travel to Cuba.

2. The U.S. government generally holds that U.S. citizens are liable for taxes, regardless of where they live. Many countries have tax treaties with the U.S. that in some cases reduces or eliminates this burden, but in general, if you are a U.S. citizen and you make enough money in a foreign country, the U.S. government will expect you to pay U.S. taxes. (Here's a Wall Street Journal blog entry on the subject: "The U.S. is the only industrialized country that requires citizens to pay income tax on offshore earnings, and many are finding the complications and cost of maintaining U.S. citizenship abroad to be increasingly burdensome.")

3. It is against U.S. law (the Foreign Corrupt Practices Act) to bribe foreign officials.

I would also guess that the U.S. sometimes has jurisdiction in foreign countries. Obvious examples would be military bases and embassies, but perhaps also in matters pertaining to U.S.-registered ships and aircraft(??).

References

• Application of U.S. Laws Abroad

Answer 2

(This is going to over-simplify things a little, but...)

Technically, as a US citizen you are covered by the laws of the US regardless of where in the world you are. However with very few exceptions, when you are outside of the US you are outside of the jurisdiction of those laws. ie, if you're a 19 year old US citizen and you're drinking in Australia then you're not breaking any law - simply because there is no law against 19 year old US citizens drinking whilst in Australia.

There are, however, exceptions.

The US government can - and has - passed laws which include a jurisdiction outside of the US. The most well known of these is the "PROTECT Act of 2003", which makes it illegal for a US citizen to partake in illicit sexual conduct abroad with someone under the age of 18. In effect, the intent of these laws was to stamp out "sex tourism", and many other countries have passed similar laws.

Answer 3

Generally, if you break a US law even though you're not in the US - you can be prosecuted if the victim is a US person, even if what you did was legal at the place where you did it.

As mentioned by @Doc, there are explicit laws regarding sex tourism, taxes, volunteering for military service, and other stuff.

Some things may be legal, but not wise. American teenagers are notorious for getting drunk everywhere they go just because they can. Now imagine yourself a bunch of kids coming into your neighborhood just to get drunk, and that's what the locals would think of you for doing that. Its not illegal, but it is still damn stupid.