Federal prosecutors have agreed to make public some secret testimony about the biggest spy case of the Cold War.

The government took the unusual position Monday as leading historical groups press for the release of grand jury transcripts in the criminal investigation of Julius and Ethel Rosenberg. Following their 1951 espionage trial for passing atomic secrets to the Soviet Union, the husband and wife were executed in 1953.

The Rosenberg case has significant historical importance that qualifies it for an exception to grand jury secrecy rules, the office of the U.S. attorney for the southern district of New York City said in court papers.

"This is very good news," said Georgetown University law professor David Vladeck, one of those seeking release of the material. "The significant point is that the government has not objected to the release of the bulk of the records we asked for, and that is far better than a glass half full."

A U.S. District Court judge in New York, Alvin Hellerstein, will have the final say. Vladeck said the historians may seek additional disclosure, leaving it to the judge to sort out disputes that could take months to resolve before any public release.

Under the approach laid out in the government's court papers, transcripts would be released for 35 of the 45 witnesses who testified to the grand jury in the Rosenberg probe. The 35 are dead or consent to disclosing their testimony.

The government opposes disclosure of testimony from the remaining witnesses who either object to disclosure or who have not died but who cannot be located.

Fifty-five years after the Rosenbergs' execution, historians still debate the extent of their espionage and whether the government may have overreached in prosecuting the couple, questions that might be addressed with an unsealing of the grand jury record of the investigation.

Separately, the government said it opposes disclosure of grand jury material from another Cold War spy case, that of Abraham Brothman and Miriam Moskowitz. That prosecution was based on Brothman's testimony before a grand jury about the nature of his relationship with an admitted Soviet spy.

Unlike the Rosenberg case, the Brothman/Moskowitz prosecution is not a case whose place in history justifies departing from the time-honored rule of grand jury secrecy, federal prosecutors argued. Brothman received a seven-year prison sentence; Moskowitz received a two-year sentence.

Among those seeking release of the material in the Rosenberg and Brothman/Moskowitz cases are the National Security Archive based at George Washington University in Washington, D.C., the American Historical Association, the American Society for Legal History, the Organization of American Historians and the Society of American Archivists.