From BBC News:
There are five national or international space agencies involved in the ISS - from the US, Canada, Japan, Russia and several European countries - and a legal framework sets out that national law applies to any people and possessions in space.
So if a Canadian national were to commit a crime in space, they would be subject to Canadian law, and a Russian citizen to Russian law.
Space law also sets out provisions for extradition back on Earth, should a nation decide it wishes to prosecute a citizen of another nation for misconduct in space.
As space tourism becomes a reality, so might the need to prosecute space crime, but for now the legal framework remains untested.
The full article is available at BBC News.