[20] Fahy received a recess appointment from President Harry S. Truman on October 21, 1949, to the United States Court of Appeals for the District of Columbia Circuit, to a new seat authorized by 63 Stat.

[20] His service terminated on September 17, 1979, due to his death in Washington, D.C.[20] Fahy defended the government in four cases that challenged aspects of internment of Japanese Americans during World War II.

Ennis urged Fahy to submit the ONI report as evidence, but because it directly contradicted the Western Defense Command's argument that it was impossible to determine Japanese American loyalty on an individual basis, Fahy withheld the information and won both cases.

[22][23][24] He also successfully argued the landmark case of Korematsu v. United States in 1944, in which the Supreme Court validated the constitutionality of the executive and military orders forcing the relocation of Japanese Americans into camp.

Ennis and other aides brought to Fahy's attention FBI and FCC reports that disproved the claims of Japanese American sabotage key to the government's argument; Fahy inserted an ambiguously worded footnote in his court brief that did not specifically mention the contradicting evidence, and the Court ruled against Korematsu.

[26][27] In the 1980s, researchers Peter Irons and Aiko Herzig-Yoshinaga uncovered evidence that Fahy deliberately suppressed information indicating Japanese Americans were not a threat to national security, and the Korematsu, Yasui, and Hirabayashi convictions were all overturned.

[32] On August 31, 1948, Hiss wrote to his lifelong friend and fellow Harvard lawyer William L. Marbury, Jr.:I am planning a suit for libel or defamation...

The number of volunteer helpers is considerable: Freddy Pride of Dwight, Harris, Koegel & Casking (the offshoot of young Charles Hughes' firm), Fred Eaton of Shearman and Sterling, Eddie Miller of Mr. Dulles' firm, Marshall McDuffie, now no longer a lawyer; in Washington Joe Tumulty, Charlie Fahy, Alex Hawes, John Ferguson (Mr. Ballantine's son-in-law) and others–but the real job is get general overall counsel and that fortunately is now settled, but we must move swiftly as so far the committee with its large investigating staff and considerable resources has been able to seize the initiative continuously and regularly.

[33] This article incorporates public domain material from websites or documents of the Solicitor General of the United States.