The Charter of the International Military Tribunal provided criminal liability for waging aggressive war, which was the main focus of the Nuremberg trial.
This case might present the use of existing legal and social frameworks to "construct an environment within which the applicability of the relevant international norms was either severely restricted or uncertain."
[7] Hugo Grotius, often considered the founder of international law, saw the principal wrong in aggression in the violation of individual rights.
[8] In 1815, Napoleon was outlawed "as an Enemy and Disturber of the tranquillity of the World" in what was considered an "Exception to general rules of the Law of Nations".
[10] In a speech on 11 November 1918, British Prime Minister David Lloyd George cited the loss of "the lives of millions of the best young men in Europe" and "the outrage upon international law which is involved in invading the territory of an independent country without its consent" as a crime for which someone should be held responsible.
[17] Soviet criminologist Aron Naumovich Trainin developed the ideas that were used to criminalize aggressive war, although he did not attract international attention until 1943.
He blamed Adolf Hitler, his cabinet, government officials, the Nazi Party and German industrialists for acts of aggression against the Soviet Union, which he described as "the most heinous crime".
[22] Although there was not much in the way of international criminal law to work from, the United States Department of War put together the legal framework for the Nuremberg trials in ten months.
[9] Both the Soviet Union, which invaded the Baltic States and Poland according to the secret protocols of the German–Soviet pact, and Western countries, which had planned an invasion of Norway, were aware that they could also be accused of acts of aggression and so they limited the definition of crimes against peace to the actions of their defeated enemies during World War II.
The judgement found that there was a premeditated conspiracy to commit crimes against peace, whose goals were "the disruption of the European order as it had existed since the Treaty of Versailles" and "the creation of a Greater Germany beyond the frontiers of 1914".
[49] All 22 defendants were charged with crimes against peace, and 12 were convicted: Hermann Göring, Rudolf Hess, Joachim von Ribbentrop, Wilhelm Keitel, Alfred Rosenberg, Wilhelm Frick, Walther Funk, Karl Dönitz, Erich Raeder, Alfred Jodl, Arthur Seyss-Inquart, and Konstantin von Neurath.
[41] The Nuremberg verdict was groundbreaking, establishing international criminal law and rejecting that act of state doctrine granted immunity for such serious crimes.
[52] Of 66 defendants charged with aggression, only three were convicted (Hans Lammers, Wilhelm Keppler, and Paul Koerner), all of them during the Ministries trial.
The Tokyo Charter defined crimes against peace as[39] the planning, preparation, initiation or waging of a declared or undeclared war of aggression, or a war in violation of international law, treaties, agreements or assurances, or participation in a common plan or conspiracy for the accomplishment of any of the foregoing.The charge of aggression was central to the trial; 36 out of 55 counts were for crimes against peace.
[66] At least 8 members of the wartime government of Ion Antonescu were sentenced in 1949 for crimes against peace, although one of them was rehabilitated by the Romanian Supreme Court on 26 October 1998.
Another Romanian sentenced for crimes against peace – Gheron Netta, Ion Antonescu's last finance minister (1 April to 23 August, 1944) – was rehabilitated by the Supreme Court on 17 January 2000.
[67][68] Arthur Greiser, a Nazi leader in Danzig and later Gauleiter in the Warthegau region annexed from Poland, was tried and convicted by a Polish court in 1946 for aggression among other charges.
[69] Historian Catherine Epstein states that the evidence that Greiser had participated in a conspiracy to wage aggressive war is weak or nonexistent.
[72] Sakai appears to have been responsible for carrying out policies designed by others, which would put him outside the Rome Statute definition of aggression.
In the early 1950s, attempts to codify the crime of aggression in a "Code of Offences Against the Peace and Security of Mankind" stalled.
The prohibition of aggression is considered a peremptory norm in customary law, such that it is binding on states that are not members of the United Nations.
[75] The most important provision in the UN Charter is Article 2(4): "All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.
[83] According to Antonio Cassese, the customary criminalization of aggression covers "planning, or organizing, or preparing, or participating in the first use of armed force by a State against the territorial integrity and political independence of another State in contravention of the UN Charter, provided the acts of aggression concerned have large-scale and serious consequences".
Other jurists require a special intent, in the form of seeking to "achieve territorial gains, or to obtain economic advantages, or to interfere with the internal affairs" of the state that is aggressed.
[90] Dinstein has argued that national prosecutions for aggression are undesirable as "the nature of crimes against peace is such that no domestic proceedings can conceivably dispel doubts regarding the impartiality of the judges.
[93] Under the Rome Statute, as amended in the 2010 Kampala Review Conference, the crime of aggression "means the planning, preparation, initiation or execution, by a person in a position effectively to exercise control over or to direct the political or military action of a State, of an act of aggression which, by its character, gravity and scale, constitutes a manifest violation of the Charter of the United Nations".
[8][104] The Rome Statute definition of aggression does not technically require harm to individuals,[105] but the relatively bloodless invasion of the Czech lands in 1939 was not prosecuted at Nuremberg.
[8][104] Philosopher Larry May maintains that serious aggressions, entailing loss of life, can be subsumed under the category of crimes against humanity.
[108] The traditional view is that only decision-makers can be held criminally responsible for aggression, rather than lower-level military personnel and ordinary soldiers.
[111] International law scholar Tom Dannenbaum argues that soldiers should have a right not to fight in illegal wars, and those who refuse to do so should be recognized as refugees.