Another example is that the crimes for which various Nazis were tried were not codified to be crimes in any legal document at the tim. Bombing civilians etc was

Another example is that the crimes for which various Nazis were tried were not codified to be crimes in any legal document at the tim. Bombing civilians etc was not, as such, banned by any international law, nor were genocide, concentration camps etc, and indeed the Allies did at times similar things themselves. So although the Nuremberg trials were fashioned as a court of law and followed legal-esque principles, there was no written law or could follow; it simply didn't exist. Hence, the tribunal was considered by some lawyers to be a mockery of court. The verdicts were effectively known ahead of time and no laws could really be cited, no legal process to follow. That said, I'm not sure what would be a better alternative.