I think it depends on whose territory you are in at the time. Over international waters? I don’t know. It would make sense that it’s either the country you are leaving or the country to are going to, or possibly the country the transportation belongs to.

Having said that, it is also a matter of negotiation. Sometimes the US will negotiate to retrieve Americans who committed crimes abroad or other nationals who committed crimes against Americans overseas. The US then prosecutes those folks on home territory. Many nations seem to think that if the accused is their national, they should prosecute. So I don’t think this kind of thing is set in stone.

In the country the mode of transportation one is on is registered, at the time of the incident. After that there are other overlaping jurisdictions, such as the country of departure, the country of your destination, and I believe lastly, the country where the person who the crime was committed against.

If your’re at sea then you are covered by maritime law in which case you can probably get away with murder.

In int’l space, you are under the jurisdiction of the country whose flag on is on the vessel.

I had my passport stolen when I was a teenager visiting Brittany. We notified the local gendarmerie; they wired my father and he bugged the US embassy in NYC. Probably a lot more complicated today.

The jurisdiction where the crime occurs.

According to my man, who is a world source of infomation, the country nearest the crime, would be responsible for the arrest and conviction.

I would say this. if the crime occured on a cruise ship, such as Carnival, the incident probably would be handled “in house”. not a major crime, but say a pocketbook theft onboard and money was taken. the cruise line would make a report and reinburse the passenger and let it go at that. being on the international waters is a difficult location for a crime to occur.

But what about a murder? Carnival can’t handle that in house…

All ships and planes transit internationally under a flag. I cannot think of any exceptions. In international waters or airspace, the flag would identify the country that would prosecute. If under their flag, then under their law. I believe Carnival sails under the Norwegian flag. Under international agreement, however, international waters and airspace in the Caribbean are under the jurisdiction of the US, policed by the US Coast Guard since the 1970s due to drug smuggling.

Scratch the data on Carnival. They are British-American under dual registry. The same with Royal Caribbean which is Norwegian-American. I believe the corporation could decide under which of the two country’s laws a case would be tried. A much more clear case would be Norwegian Cruise Lines which operate their ships under the Norwegian flag. A crime committed aboard an NCL ship in international waters, no matter where on the globe, would be tried under Norwegian law. Under maritime law, if it is a minor crime such as drunk and disorderly, petty theft, or minor property damage, the captain could adjudicate aboard ship and the purser could actually effect short-term incarceration (usually house arrest in one’s cabin) or a fine. If it is a major crime, such as murder, the perpetrator would be confined under guard, taken off at the next port of call, put on a plane and tried in Oslo under the laws of Norway.