A set of coded messages between Tokyo and overseas Japanese embassies and consulates in 1940–41 that were intercepted, then decoded and translated by American cryptologists in 1941 and that served as a source of intelligence. A small subset of these cables mentioned Japanese Americans in the context of Japanese efforts to establish espionage rings in the U.S. Since the 1980s, these cables have been repeatedly cited as evidence that justifies the mass removal and incarceration of all Japanese Americans from the West Coast. These claims have been refuted by a wide range of historians.
MAGIC was the code name of some 4,000 diplomatic messages between Japanese government officials in Tokyo and Japanese overseas embassies and consulates that were intercepted and decoded by American intelligence personnel by early 1941. The top-secret messages were made accessible to a circle of high-level American officials including Secretary of War Henry Stimson and his assistant John McCloy , Army Chief of Staff George C. Marshall , and President Franklin D. Roosevelt . The raw intelligence contained in the messages was one source among others accessible to these leaders.
A few of these messages dealt with Japanese efforts to gather intelligence within the U.S. and the potential recruitment of Japanese Americans. A January 30, 1941, message to Japanese consulates in the U.S. instructed them to pursue espionage efforts and authorized them to recruit Nisei on the one hand, but advised against it at the same time, suggesting the "utilization of U.S. citizens of foreign extraction (other than Japanese), aliens (other than Japanese), communists, Negroes, labor union members, and anti-Semites, in carrying out the investigations..." 
The most cited message, emanating from Los Angeles and dated May 9, 1941, came as a result of a request from Tokyo for a status report on efforts to establish an intelligence operation in the U.S. It read in part:
"We are doing everything in our power to establish outside contacts in connection with our efforts to gather intelligence material. In this regard, we have decided to make use of white persons and Negroes, through Japanese persons whom we can't trust completely. (It not only would be very difficult to hire U.S. (military?) experts for this work at the present time, but the expenses would be exceedingly high.) We shall, furthermore, maintain close connections with the Japanese Associations, the Chamber of Commerce, and the newspapers. 
"We shall maintain connection with our second generations who are at present in the (U.S.) Army, to keep us informed of various developments in the Army. We also have connections with our second generations working in airplane plants for intelligence purposes."
Years later, the Department of Defense published the MAGIC cables in a five-volume set titled The "MAGIC" Background of Pearl Harbor in 1978.
Claims and Counterclaims
In 1983, the Commission on Wartime Relocation and Internment of Civilians (CWRIC) issued their report, Personal Justice Denied . That report found the mass incarceration of Japanese Americans was "not justified by military necessity, and the decisions which followed from it—exclusion, detention, the ending of detention and the ending of exclusion—were not founded upon military conditions," and that the causes were "race prejudice, war hysteria, and a failure of political leadership."  The CWRIC later issued recommendations that included a governmental apology and $20,000 reparations to Japanese American survivors of the wartime incarceration. Legislation to implement these recommendations was subsequently considered by Congress.
Shortly after the publication of the report and recommendations, national media picked up on accusations by David Lowman, a career intelligence officer for the National Security Agency, that the CWRIC had failed to consider the evidence of "Japanese-American spying" supposedly revealed in the MAGIC cables. Lowman went on to testify before a congressional subcommittee considering the redress legislation, citing the MAGIC as evidence that "first and second generation Japanese had been successfully recruited and were now spying on shipments of airplanes and war material in the San Diego and San Pedro areas."  Lowman and other anti-redress movement activists continued to cite MAGIC at every opportunity. Lowman was even called as a witness at an evidentiary hearing for Gordon Hirabayashi's coram nobis suit to make the government's case that the exclusion and curfew were justified. As legal historian Peter Irons reports, "aggressive questioning by [Hirabayashi lawyer] Camden Hall forced Lowman to confess that none of the "Magic cables" showed that Japanese Americans had provided intelligence to Tokyo. One cable Lowman called an 'espionage nugget' turned out to contain material printed in the Los Angeles Times." 
Lowman's book titled MAGIC: The Untold Story of U.S. Intelligence and the Evacuation of Japanese Residents from the West Coast during WW II was posthumously published in 2001. More recently, the MAGIC evidence was central to the argument of bestselling author Michelle Malkin in her book In Defense of Internment: The Case for 'Racial Profiling' in World War II and the War on Terror (2004).
Professional historians have largely dismissed the significance of the MAGIC Cables with regard to Japanese American exclusion and incarceration on two broad fronts. Many cite the ambiguous and unreliable nature of the cables themselves and criticize Lowman and his successors with overreaching in their interpretation of them. Many chroniclers have noted that the intercepts seem to indicate hopes and intentions rather than actual accomplishment when it comes to intelligence work involving Japanese Americans.  As James C. McNaughton, former command historian of the U.S. Army wrote in his review of Lowman's book, "Lowman's book rehashes old arguments and gives a tortured reading of the available intelligence sources. He errs in giving absolute primacy to communications intelligence, no matter how ambiguous. His polemics should be viewed as symptomatic of the lingering bitterness stemming from Pearl Harbor and the emotions raised by apologies and compensation." 
Historians also dispute Malkin's contention that MAGIC was influential in the decision to exclude. Key architects of exclusion such as General John L. DeWitt did not have access to MAGIC, while War Department leaders Stimson and McCloy, who did have access, opposed mass removal almost until the end.  And as Greg Robinson notes, "Throughout all the confidential memoranda and conversations taking place within the War Department at the time of the decision on evacuation, transcripts which show people speaking extremely freely, the MAGIC excerpts are not mentioned a single time. In particular, there is no evidence that President Roosevelt ever saw or was briefed on the MAGIC excerpts the author mentions, let alone that he was decisively influenced by them." 
Despite—or perhaps because of—their ambiguous nature, the MAGIC cables have served opponents of the redress movement well and will no doubt continue to be cited by those seeking to justify the mass removal and incarceration of Japanese Americans.
For More Information
Commission on Wartime Relocation and Internment of Civilians. Personal Justice Denied: Report of the Commission on Wartime Relocation and Internment of Civilians . Washington, D.C.: Government Printing Office, 1982. Foreword by Tetsuden Kashima. Seattle: University of Washington Press, 1997
Herzig, John A. "Japanese Americans and MAGIC." Amerasia Journal 11.2 (fall/winter 1984): 47-65.
McNaughton, James C. "Japanese Americans and the U.S. Army." Army History 59 (summer–fall 2003): 4–15.
"Muller and Robinson on Malkin." IsThatLegal Blog . http://www.isthatlegal.org/Muller_and_Robinson_on_Malkin.html .
Murray, Alice Yang. Historical Memories of the Japanese American Internment and the Struggle for Redress . Stanford: Stanford University Press, 2008.
Robinson, Greg. A Tragedy of Democracy: Japanese Confinement in North America . New York: Columbia University Press, 2009.
- Cited in Greg Robinson, A Tragedy of Democracy: Japanese Confinement in North America (New York: Columbia University Press, 2009), 46.
- Cited in Personal Justice Denied: Report of the Commission on Wartime Relocation and Internment of Civilians (Washington, D.C.: Government Printing Office, 1982. Foreword by Tetsuden Kashima. Seattle: University of Washington Press, 1997), 473.
- Personal Justice Denied , 459.
- Alice Yang Murray, Historical Memories of the Japanese American Internment and the Struggle for Redress (Stanford: Stanford University Press, 2008) 357.
- Peter Irons, Justice at War: The Story of the Japanese American Internment Cases (New York: Oxford University Press, 1993), 375.
- See for instance John A. Herzig, "Japanese Americans and MAGIC," Amerasia Journal 11.2 (fall/winter 1984): 58; and Robinson, A Tragedy of Democracy , 45–46.
- James C. McNaughton, "Japanese Americans and the U.S. Army," Army History 59 (summer–fall 2003): 11.
- "In Defense of Internment, Part 5," Is That Legal blog post by Greg Robinson, accessed at http://www.isthatlegal.org/Muller_and_Robinson_on_Malkin.html#IDOI%205 ; Robert Asahina, Just Americans: How Japanese Americans Won a War at Home and Abroad (New York: Gotham, 2006), 267–70.
- Robinson, "In Defense of Internment, Part 5."