The International Military Tribunal (IMT) explicitly ruled out a tu quoque (you too) as an acceptable tactic for the defense. The IMT defense team did try to engage in a quasi-tu quoque defense throughout the proceedings, but this was unsuccessful save in one case.

The general position of the court was that any Allied actions could not be divorced from the larger context of the war. Additionally, the court's position was that Allied actions like the Dresden bombing were means to an end (Axis defeat) while Axis military actions fell outside the general norms of warfare and was directed to punish or destroy the enemy populations irrespective of such destruction's impact on military operations. The only real instance where in the IMT where tu quoque made any real headway was in the charges against Dönitz's conduct of the submarine war. His defense team argued that the German understanding of the laws on unrestricted submarine warfare were much the same as those of the Allies and had managed to secure an affidavit from from Admiral Chester Nimitz saying much to that effect. This was only a partial victory for tu quoque as it led to this element of his prosecution being dropped by the Tribunal, not an acquittal (and there was still enough incriminating material to convict Dönitz on other charges).

The tu quoque defense did receive a second wind of sorts in what are generally known as the Subsequent Nuremberg Proceedings, or the National Military Tribunals (NMT), run by the US military government. These trials were conducted after the IMT and had a much lower public visibility, so the defense tended to indulge in a tu quoque defense. The Tribunals were much more sensitive to the charges that the tribunals were a form of victor's justice. The court of the Ministries Trial- Volume 12 of the Green Series outlined this more flexible approach:

These Tribunals were not organized and do not sit for the purpose of wreaking vengeance upon the conquered. Was such the purpose, the power existed to use the firing squad, the scaffold, or the prison camp without taking the time and putting forth labor which have been so freely expended on them, and the Allied Powers would have copied the methods which were too often used during the Third Reich. We may not, in justice, apply to these defendants because they are Germans standards of duty and responsibility which are not equally applicable to the officials of the Allied Powers and to those of all nations. Nor should Germans be convicted for acts or conducts which, if committed by Americans, British, French, or Russians would not subject them to legal trial and conviction

But despite this flexibility, tu quoque really did not achieve that much in the NMT. The defense in the RuSHA case, which tried members of the Race and Resettlement Bureau's Germanization campaign, argued that actions both the interwar unmixing of ethnic populations in Greece and the ongoing expulsions of Germans and Volksdeutsche from Eastern Europe were a sign that RuSHA was not acting outside of international norms. Likewise, during Krupp and Flick trials, the industrialists' defense teams cited the Allies' dismantling of German industry as evidence that their governments were little different from the Third Reich's policies of booty and extraction of non-German wealth from conquered territories.

Dresden and the atomic bombings featured quite prominently in the Einsatzgruppen case. The Dresdener SS-Brigadeführer Erich Naumann and commander of Einsatzgruppe-B argued in his statement pleading not guilty to the charges:

The war has shown that not only the Germans but also the Allied soldier receives and executes severe and severest orders. How could it be possible otherwise that my home town of Dresden, which housed no factories nor any installations of war importance within her boundaries, should be destroyed within 36 hours, and, thus more than 200,000 defenseless human beings, mostly old people, women and children were killed, buried, or cruelly wounded? How could it otherwise have been possible that the old city of my last garrison, old Nuremberg, had been turned into a rubble heap? How would it have been possible that the first atom bombs were thrown on Japan, and thousands and thousands of defenseless people were killed and that through the very conse­quences of the atom bomb even the unborn generation will have to suffer?

On both sides soldiers executed their orders, orders of their highest superiors, even if it was not in accordance with their con­science, when they had received the orders, with the reason that they were necessary in order to reach the war aim.

Yet despite the greater flexibility of the Tribunals for a tu quoque defense, it gained very little traction for the defense. The judgements in the Ministries Trial upheld the idea that Allied behavior was a measuring stick for the degree of guilt on the part of the Germans and not an excuse. In the High Command Case, tu quoque was used to mitigate levels of guilt as it was in other NMT. The Einsatzgruppen judges ruled that atomic bombing, although terrifying, fell within the bounds of international norms of warfare:

It was argued in behalf of the defendants that there was no normal distinction between shooting civilians with rifles and killing them by means of atomic bombs.There is no doubt that the invention of the atomic bomb, when used, was not aimed at noncombatants. Like any other aerial bomb employed during the war, it was dropped to overcome military resistance.Thus, as grave a military action as is an air bombardment, whether with the usual bombs or by atomic bomb, the one and only purpose of the bombing is to effect the surrender of the bombed nation. The people of that nation, through their representatives, may surrender and, with the surrender, the bombing ceases, the killing is ended.

The Einsatgruppen tribunal's dismissal of the defense's tu quoque argument highlights one of the fundamental differences between Allied war crimes and those of their enemy. At best, tu quoque showed the Allies were guilty of hypocrisy and did not mitigate Germans' guilt for their wartime actions. The sometimes reflexive use of tu quoque by the likes of Naumann also indirectly incriminated German war criminals in one of the chief charges of the Tribunals. One of the central arguments the Allies made was that the indicted made no differentiation between soldiers and saw the atrocities committed against civilians as an extension of normal military operations. By arguing that they were little different from the pilots and bombardiers of the Allied armies and were soldiers performing their duties, the defendants inadvertently proved part of the prosecutions' case.

Sources

Bazyler, Michael J., and Frank M. Tuerkheimer. Forgotten Trials of the Holocaust. New York: New York University Press, 2014.

Davidson, Eugene. The Trial of the Germans: An Account of the Twenty-Two Defendants Before the International Military Tribunal at Nuremberg. New York: Macmillan, 1966.

Heller, Kevin Jon. The Nuremberg Military Tribunals and the Origins of International Criminal Law. Oxford: Oxford University Press, 2011.

Priemel, Kim Christian, and Alexa Stiller. Reassessing the Nuremberg Military Tribunals: Transitional Justice, Trial Narratives, and Historiography. New York: Berghahn Books, 2012.