For the Class A war criminals the USG and its allies decided to hold accountable through prosecution, the forum was a newly established, ad hoc international military tribunal created outside the UN through an executive order by MacArthur acting as the SCAP.107 This tribunal had limited subject-matter (crimes against peace, war crimes, and crimes against humanity), temporal (crimes committed since 1928, when Japanese assassinated Chang Tso-lin, a Chinese warlord), and personal (major war criminals in the Far East) jurisdiction. Unlike the immediate post-Cold War ad hoc tribunals would,108 the IMT and the IMTFE did not feature any institutional overlap.
Unlike the case of the principal suspected Nazi atrocity perpetrators, the USG seriously considered at least one other option for addressing some Class A Japanese war criminals and Hirohito: unconditional amnesty. While the Allies, including the USG, were trying thousands of Classes A, B, and C Japanese suspected of committing atrocities during WWII, the USG also provided amnesty to other Japanese who were suspected of similarly heinous crimes.109
The USG explicitly extended unconditional amnesty to Japanese Emperor Hirohito, who was never taken into Allied custody.110 The U.S. Joint Chiefs of Staff specifically ordered MacArthur not to attempt to apprehend Hirohito as MacArthur sought to capture individuals who would eventually be tried before the IMTFE.111 MacArthur thus declined to request or even support Hirohito’s abdication.112 As a result, on June 18, 1946, Keenan announced that Hirohito would not be charged, thus publicly and officially exonerating the emperor of responsibility for Japan’s actions during WWII.113
A second grant of amnesty occurred after MacArthur selected twenty-eight individuals to indict before the IMTFE from all of the Class A war criminals he detained at Sugamo Prison.114 The Allies, led by the USG, eventually released (by December 24, 1948) and never held accountable the more than fifty Class A war criminals remaining, many of whom eventually returned to Japanese politics.115 Thus, for those Japanese Class A war criminals the USG arrested but then decided not to hold accountable through the IMTFE, the USG implicitly extended unconditional amnesty.