It's unlikely any of us will be a defendant or complainant in a crime allegedly committed outside the earth anytime soon.
However, a recent United States case triggered discussion about how such matter might be dealt with in the future.
Astronaut Anne McClain was recently involved in a six-month mission to the International Space Station (ISS).
While she was in space she accessed the account of her estranged spouse from the ISS, and it has been alleged that she did so illegally as a form of identity theft.
Lieutenant Colonel McClain defended herself on Twitter, explaining that she and her partner had been going through a "painful, personal separation", saying that the allegations had been a fabrication. She insisted that she accessed her bank account legally, to make sure that there was enough money to pay bills and care for her partner's son.
"She strenuously denies that she did anything improper," her lawyer said adding that the astronaut was "totally cooperating".
Lieutenant Colonel McClain's ex-partner, however, has said he is committed to pursuing her for identity theft, filing a complaint with the Federal Trade Commission and another with NASA's Office of Inspector General.
There are five international space agencies involved in the ISS – the US, Canada, Japan, Russian and the European Space Agency. It has been agreed that national law governs the people and possessions in space.
As stated by an intergovernmental agreement by these partner nations, "Canada, the European Partner States, Japan, Russia, and the United States may exercise criminal jurisdiction over personnel in or on any flight element who are their respective nationals."
This would mean that US astronauts would be governed by US law while Russians would be governed by Russian law. This is known as "active-nationality" jurisdiction.
There has, as yet, been no need to consider situations where there is a conflict of laws, such as when a Russian national, governed by Russian law, comes onto a US vessel, governed by US law. Also, there may be issues of who particularly could carry out a prosecution when two different nationality astronauts have a dispute.
The intergovernment agreement states that, if the victim of a crime committed on the ISS was a citizen of a different nation, and if the US refused to prosecute the perpetrator, that other nation's criminal law would apply. This is known as "passive-nationality" jurisdiction.
For the purpose of Lieutenant Colonel McClain though, the short answer would be that a US astronaut aboard the ISS with a US victim would clearly be a matter of US criminal jurisdiction.
Broader jurisdictional issues
If this alleged crime had of occurred outside of the confines of the ISS, there would be different legal principles in play.
Space, like the high seas, operates under the principle of res communis, meaning that no specific country can lay claim to it. National laws will still apply, but not as a result of ownership of the territory, as is the case with most laws.
Space is governed by five international treaties, known informally as the Outer Space Treaty, the Rescue Agreement, the Liability Convention, the Registration Convention, and the Moon Agreement.
The Outer Space treaty would most likely apply to crimes committed in space (and not on the ISS). This treaty requires that space exploration is not subject to any claim of national sovereignty and any interstellar bodies like the moon are to be used for only peaceful purposes.
The treaty deals with crimes in a similar way to those committed on the high seas. Basically, a spacefaring criminal would generally be subject to the law of the country of which they are a citizen, or the country aboard whose registered spacecraft the crime was committed.
Once again, however, the interpretation of this treaty has not been tested and there would be issues if there were crimes involving two citizens of different nations or where there was a private citizen flying another country's spacecraft.
An issue for the future
In 2001, Dennis Tito became the first space tourist. Since then, only seven private citizens have paid to go to space.
Virgin Galactic, however, has designs on expanding the scope of space tourism, promising "a regular schedule of spaceflights for private individuals and researchers" in the future.
Multinational investment bank UBS expects the broader space industry, which is worth about $400 billion today, will double to $805 billion by 2030 when accounting for upcoming innovations.
"While space tourism is still at a nascent phase, we think that as technology becomes proven, and the cost falls due to technology and competition, space tourism will become more mainstream," UBS analysts Jarrod Castle and Myles Walton have commented.
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