Jack Herzig, 83, a lawyer who with his wife played an instrumental role in gaining redress from the United States for the internment of Japanese Americans during World War II, died Aug. 21 at his home in Gardena, Calif. He had colon cancer.

Between 1942 and 1945, the federal government interned more than 120,000 ethnic Japanese, most of whom were born in the United States, amid widespread anti-Japanese sentiment.

The U.S. Supreme Court in the 1944 case of Fred Y. Korematsu v. the United States upheld the constitutionality of the decision to imprison Japanese Americans during the war. Korematsu, who in 1942 was a 23-year-old welder living in Oakland, Calif., refused to report to an internment camp. He was arrested, convicted of violating the internment order and was sent to a camp in Utah.

Mr. Herzig and his wife, Aiko Yoshinaga-Herzig, in the 1980s uncovered documents in the National Archives and other repositories that showed government prosecutors suppressed, altered and destroyed evidence during its prosecution of Korematsu.

The documents enabled a team of largely Asian American lawyers to file a petition for writ of coram nobis, a rarely used legal strategy to overturn convictions after new evidence is discovered.

In November 2003, U.S. District Court Judge Marilyn Hall Patel from the bench exonerated Korematsu and blasted the government for basing its decisions on "unsubstantiated facts, distortions and the [opinions] of one military commander whose views were seriously tainted by racism."

The ruling helped secure a presidential apology and financial reparations for former internees.

Korematsu, who died in March, was given the nation's highest civilian honor, the Presidential Medal of Freedom, by Bill Clinton in 1998.

"Jack Herzig is one of those unrecognized giants of redress for Japanese Americans," said Dale Minami, a San Francisco Bay area civil rights lawyer who helped form the legal team to exonerate Korematsu. "He and his wife found the documents that essentially incriminated the United States government and undercut the whole rationale of military necessity for internment."

Mr. Herzig was committed to social justice and also denounced the discrimination that surfaced during the Persian Gulf War and more recently during the war with Iraq, Minami said.

Besides his wife, survivors include four children.