One would imagine, if one were in Space, that the vessel you were travelling in, would be bound by the laws of its originating Nation
A US vessel operates under US law, a Chinese vessel under Chinese law, etc
Only logical
If one were on the Moon, I would imagine it to be viewed under a multi-national treaty, as the Antarctic areas are
Mars the same, etc
But, eventually in Space, it follows human nature.....there will be Space Pirates who operate under their own laws, aaarrrrgh!