Acts agains humanity and warcrimes can be filed in any country and the same person can be convicted for exactly the same Crime in for ex. USA, the in Germany, and then in France, and then in Sweden, UK, etc, etc. there is not limit on how many sentences.
As it is a crime against Humanity, it is in the interest of Humanity that the Crime is put under a trail.
If the US Federal Court have ruled it has no Juristiction in this case, it can not bring it up. This does not mean it is not a valid case, only that the US Federal Court can not handle it.
Germany have extreme Laws on just this: Crimes against humanity and warcrimes , due to the aftermath of WWII and the Nurnberg trails.
Letting one case go, will mean all cases need to go...........
International Court of Law is where Countrys are put under trail against breaking international law as stated in UN charta and international treatys.
The international wartribual of Haag, is where the complaint for this kind of crimes should be filed.
But as USA Goverment deny its Juristiction on handeling warcrimes/crimes against humanity conducted by US citizens, this is not possible either.
USA could say that German Federal Court does´nt have the Juristicion as well. But that will mean a whole lot of complications to a lot of verdicts against WWII convicted warcriminals and also to the presence of US personal on German territory.
Leaves only one option in the end, does´nt it?