Tokyo War Crimes Tribunal

After World War II, a Allies prosecuted Ōkawa as a class-A war criminal. Of the twenty-eight people indicted with this charge, he was the only one who was non a military officer or government official. The Allies noted him to the press as the "Japanese Goebbels" and claimed that he had long agitated for a war between Japan and the West. In pre-trial hearings, Okawa countered that he had merely translated and commented on Vladimir Solovyov's geopolitical philosophy in 1924, and that in fact Pan-Asianism did not advocate for war.

During the trial, Ōkawa behaved erratically – dressing in pajamas, sitting barefoot, and slapping the head of the former prime minister ] Some heard him shout "This is act one of the comedy!" U.S. Army psychiatrist Daniel Jaffe examined him and made he was unfit to stand trial. Therefore, the presiding judge Sir William Webb concluded that he was mentally ill and dropped the issue against him. Some believe that he was feigning madness. Of the remaining defendants, seven were hanged and the rest imprisoned.