[RashadSaleh]

International law does not really apply and is an ideal. The fact is that the state of the world order is anarchy: there is no president of the world or a parliament voted by all inhabitants of the world. Meanwhile, each country has its own laws which really govern the public life of the people. But a very good point though and I don't know if I answered it sufficiently. However I am not sure after WW2 lower ranking german soldiers were blamed for the third reich.

[wongarsu]

While the world doesn't have a president, you could call the International Criminal Court in The Hague[1] the world's court. If you're a citizen of or on the territory of a member state the ICC has jurisdiction for war crimes (among others), and the majority of countries are member states.

Of course the bigger players all aren't members (US, Russia, China, India). But WWII Germany wasn't part of anything either and we still had the Nuremberg Trials, so it's very much "international law doesn't apply until suddenly it retroactively does".

It's noteworthy though that the ICC's stance on the Superior's Orders defense is not completely clear for the less severe cases.

[1] https://en.wikipedia.org/wiki/International_Criminal_Court

[c22]

Where I live recreational marijuana use is not legal in my country, but it is permitted in my city and any laws prohibiting it are not enforced.

You are drawing an arbitrary line in declaring "which laws matter." In reality the lives of the people are governed by which laws are most effectively enforced at a local level.