Unveiling the Yokohama Trials: The Forgotten Justice of Post-War Japan

by Rania Alaoui

The International Military Tribunal for the Far East, commonly known as the Tokyo Trials, is widely credited for delivering justice against war criminals from the Pacific War. Less known are the Yokohama Trials, held an hour outside Tokyo, which convicted over 850 Class B and C defendants across 319 cases, yet are often deemed ‘lesser’ compared to the Tokyo Trials’ 28 Class A defendants. Major General Tasuku Okada, a notable Yokohama defendant, was executed for ordering the deaths of 38 American POWs. Other defendants, including camp guards, lieutenants, and minor officials, faced charges for abusing POWs and civilians. Unlike the Tokyo Trials’ focus on high-ranking generals, the Yokohama Trials targeted lower- and mid-level ranks. Their 319 cases demonstrate that justice was pursued across ranks, holding both those directly responsible and those liable under command responsibility accountable for atrocities.

Sketching out the Trials
Efforts to codify a system for convicting war criminals began in 1944, as the Allied powers anticipated victory. Facing challenges in aligning international law with jus in bello (laws of war), they crafted the Charter of the International Military Tribunal for the Far East (IMTFE), implementing the Potsdam Declaration’s call (July 26, 1945) for “stern justice” against war criminals, including those who mistreated prisoners. Japan formally surrendered to the Allied Powers on September 2, 1945, aboard the USS Missouri in Tokyo Bay, marking the end of World War II’s Pacific theater, with the United States signing on their behalf. The Allies established the IMTFE to punish violations of the laws of war. Comprising legal scholars and judges, the tribunal sorted defendants into Class A (leadership) and Class B/C (perpetrators). The Tokyo Trials prosecuted 28 Class A war criminals. The Yokohama Trials, handling 319 cases, tried soldiers and officials, demonstrating justice across ranks.

The Presence of the U.S. Eighth Army in Yokohama
The Yokohama Trials, less publicized than the Tokyo Trials, were rigorous, addressing crimes against Allied POWs and civilians from multiple nations, though primarily U.S.-led. The trials were conducted from 1946 to 1949, during the height of the United States’ occupation of Japan,  they were overseen by Lt. General Robert L. Eichelberger’s 8th Army, under General Douglas MacArthur’s authority. Furthermore, as historian Philip Picagallo notes, the Yokohama Trials comprised tribunals that tried defendants for crimes against multiple nations. These nations represented thousands of Allied POWs as well as civilians from Japan’s former territorial conquests.

B-29 Bomber Crew- Majority of Them were Vivisected at Kyushu Imperial University Source: Mansell Website

The 8th Army ensured suspects had defense and translation services, with accusations requiring evidence, despite Japanese efforts to destroy POW records.  Investigating numerous undocumented war camps was challenging. In U.S. v. Sanji Okido et al., defendants faced charges for murdering American airmen at Osaka Kempei Tai (1942–1945), with evidence of burned records. Okido was sentenced to life imprisonment at hard labor; the rest got varying prison terms.

At the Tribunal
While waiting for trial, Class B/C Suspects were held alongside Class A criminals at Sugamo Prison near Tokyo. American defense attorneys reported that the 8th Army used its power to educate suspects held at Sugamo on ‘American values of democracy,’ a practice that proved more common as the trials waned. Mass trials, like U.S. v. Sanji Okido et al., were common in Yokohama, aiding U.S.-Japan relations by expediting justice before the 1951 San Francisco Peace Treaty. Critics argued mass trials limited evidence reconsideration, but many sentences were reviewed, with some commuted.
An example is Case 258, where after reviewing the initial hearing, a judge advocate commuted the death sentences of 34 out of 41 defendants to prison terms.

Of 996 Yokohama defendants, 854 were convicted, 142 acquitted, 124 sentenced to death (73 commuted), 63 to life imprisonment, and 667 to varying terms. Like in Case 258, many who faced execution had their sentences commuted. Others who were recommended for life imprisonment were pardoned by the new Japanese government after the 8th Army lost its authority over the military tribunal. 

Judge Advocate Allan R. Browne’s recommendations for the trials he presided over help modern historians understand the motivations behind the Yokohama Trials. A notable entry is on Matsukichi Muta, a former civilian employee of the Japanese Army who was accused of abusing POWs. On April 25, 1947, Judge Advocate Browne sentenced Muta to death by hanging. Browne agreed to a review of the sentence, but upheld the verdict after considering two premises: first, that just because the testimonies against Muta lacked specifications did not mean they were invalid. Also, Muta’s punishment would show that even those involved in minor instances of abuse weren’t exempt from justice. The second premise appears to come directly from Muta’s brother, who wrote a letter to Browne describing how the Yokohama War Trials would help eliminate militarism from Japanese society. 

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Document outlining plans to prosecute convicted war criminals. https://pacificatrocitiesedu.reclaim.hosting/items/show/908

Despite not receiving substantial attention from the media, in comparison to the Tokyo Trials, the Class BC Trials in Yokohama accomplished many of the United States’ goals in East Asia. They helped draft international law into legislation while encouraging the application of Western democratic principles in Japan. The trials held 996 individuals accountable for war crimes, with 854 convictions, demonstrating that even low-ranking perpetrators faced justice, setting precedents that likely influenced modern military training on war crimes accountability.


Sources
History of the Non-Military Activities of the Occupation of Japan, 1945 through December 1951, Vol. 7. 1996. Nihon Tosho Center. https://www.ndl.go.jp/constitution/e/library/06/202bunshoko.html
Lee, Stella. Yokohama Trials: Matsukichi Muta. 2007. U.C. Berkeley War Crimes Studies Center. https://www.ocf.berkeley.edu/~changmin/Japan/Yokohama/Reviews/PT-yokohama-index.htm
Pennington, Lisa Kelly. The Pacific War Crime Trials: The Importance of the Big Fish vs. the Small Fry. 2012. Old Dominion University.
Piccigallo, Philip R. The Japanese On Trial: Allied War Crimes Operations in the East, 1945-1951. 1979. University of Texas Press.
Potsdam Declaration. 1945.
Stoffell, Christy Merrifield. In the Shadow of Nuremberg: The Creation of the Yokohama Trials of Class B and C War Criminals. 2003. University of Tennessee, Knoxville. 
Various creators for different sources and materials. War Crimes Source Material, 1943-1945. Accessed 2025. Pacific Asia War Archive. https://pacificatrocitiesedu.reclaim.hosting/items/show/908.