Let's say that there's a joint mission to the International Space Station, composed of American and British astronauts.
They get along well for the first few days, but tensions grow, and eventually an American crew member kills a one of the British group.
How would the investigation and trial be conducted? Who would investigate? What court would the defendant be tried in?
Is there some kind of "space rulebook" that spells out what to do with murder, or crime in general?
Maritime law applies in space which means jurisdiction lies with the country of registration of the vessel. So, if the crime occurs in transit then Russia has jurisdiction since, at present, all transportation is provided by Russian Soyuz capsules.
The ISS itself is governed by a number of international treaties, MOU and bi-lateral agreements. In essence:
The basic rule is that 'each partner shall retain jurisdiction and control over the elements it registers and over personnel in or on the Space Station who are its nationals' (Article 5 of the Intergovernmental Agreement).
Same as high seas. It's international space. The flag of the vessel, or the country of the victim usually handles prosecution but there are additional hurdles.
