Here is the case: You have been retained to prosecute a man for his involvement (ample evidence in hand) in the murder of hundreds of thousands of Jews. It is post 1945. You are in Germany. You are a USA attorney. After you present all of the facts of what he did in the mass murders, the Defense attorney raises the following counter points and defense: (1) The execution of Jews was "legal" in the nation/society of Germany during the time period the defendant did so. (2) One nation, or a group of nations, or even another society, does not have the right to impose its laws on another. Thus, what is illegal in USA, can be legal in another country, and logically, the USA courts cannot cross national borders and impose its laws. Examples include Prohibition, speed limits, voting rights, abortion, divorce, etc. For example, the current (at that time) segregation of whites and blacks in schools, in USA, is illegal in Egypt. Egyptian Govt cannot enter USA and prosecute USA citizens. (3) Following ones own country's laws, as directed, is 'legal' even though it maybe unacceptable to another. Victory in a war does not automatically provide for the imposition of a different set of morals on the defeated country. (4) To not obey the directives of the Government and leadership of Germany, pre 1945, would in essence have been "illegal", therefore, what is illegal yesterday cannot be deemed legal after the fact and visa versa. (5) As a citizen of a nation, the defendant is required to follow the laws of that nation. That applies to all citizens of all nations in the world. By what authority does another nation have the right to impose, retroactively, another set of laws on a citizen of another nation?