From the point of view of the US government, there are certain things that US Citizens are not allowed to do, even outside the US. Two of the most commonly known apparently are engaging in financial transactions with respect to Cuba, and having sex with children. These are illegal for a US citizen to do even if they are in an area of the world where local law permits it.
If Federal authorities catch a person under one of these laws for engaging in illegal conduct outside of the US, in what jurisdiction in the US are they tried?
E.g. John P. Cigarhead goes to Europe and buys and smokes lots of Cuban cigars. He then returns to the US empty-handed, having smoked or sold all of his Cuban cigars before re-entering US territory. Somehow, US authorities are alerted to this and they find Probable Cause to arrest John. In what jurisdiction in the US would the trial be held? Is there any law that specifies how to pick the jurisdiction in which the trial will be held and from which the jury pool will be selected? Is it Washington, DC? Is it the point of return (e.g. if John re-entered the US by taking a plane from London to Miami, then the trial might be held in Miami). Is it at the whim of the prosecutor or police or the choice of the accused? Remember that jurisdiction normally is an important element of trials - you can’t normally arrest someone fr allegedly committing murder in Chicago and try them in a court in Bangor, Maine.
Equivalent answers for other countries would also be welcome.
Shooting from the hip, I’d guess that any federal court where D. happened to be present would have jurisdiction (and probably his home district as well, if that’s different). For particular extra jurisdictional crimes, there might be a statutory grant of jurisdiction to a particular court, although of course there might be 14th Amendment objections to that.
As far as picking which jurisdiction of those allowable to actually prosecute the crime, I’d expect for the garden-variety ones, it’d go on the regular docket of the AUSA (Assistant United States Attorney – the federal prosecutors corps) wherever arrest was made. For something high profile, there might be negotiation (or ultimately marching orders from D.C.) among the USA’s to try and pick the most favorable jurisdiction for conviction.
I’d assume that for a US resident, as with your example; Mr. Cigarhead would be tried in his state of residency.
As for individuals who are resident abroad; that’s an interesting question. To get a residency permit in Turkey I had to have a US permanent address; I used my mother’s. So while I’m not actually a Massachusetts resident, and I certainly can’t imagine any reason for me to either trade with Cuba or have sex with children, supposing I were a mogul or a pervert I imagine that I’d be tried in Massachusetts.
For US citizens who are permanent residents abroad with no US address, I imagine that if the US wanted to try them, they’d have a rather limited window of opportunity, and would thus try them wherever they were arrested.
This of course is all speculation. If you’re really curious, you’re welcome to try it yourself.