For several hundred years, it has been a basic role of our legal system that "all crime is local". For another country to seek to punish conduct not performed within its borders has been seen as an unacceptable attempt to undermine the sovereignty and authority of the country of residence of the person accused. The era of colonial power was perhaps an exception to this, but one justified on the basis that the colonial power included all its empire within its own territory.
Hiscock, Mary E.
"The International Criminal Court: What it means to Australia,"
The National Legal Eagle:
2, Article 5.
Available at: http://epublications.bond.edu.au/nle/vol8/iss2/5