FOR MORE THAN 30 years, prevailing judgments of Julius and Ethel Rosenberg have tended to reflect the nation's ideological climate far more than they have reflected the facts of the case itself. In the 1950s, with public animosity toward the left at a fever pitch and with concern about Russian intentions and capabilities a national obsession, most Americans were inclined to believe that these obscure New York communists were, in fact, "master spies" whose delivery of atomic secrets to the Soviet Union was responsible for the end of America's nuclear monopoly and even the outbreak of the Korean War. By the late 1960s, the rise in popular mistrust of the government and the romanticization of postwar radicals by the New Left had helped win wide support for the Rosenbergs' own claim that they were innocent martyrs, deliberately framed and executed for their political beliefs.

Now, of course, the ideological climate has shifted once again. And one might, therefore, reasonably expect a new book on the Rosenbergs to serve as most other books on this case have served: as a weapon in contemporary political battles. Happily, that is not the case with this sensitive, absorbing, and exhaustively researched study by Ronald Radosh and Joyce Milton. Rather than use the Rosenbergs to settle old ideological scores, they have risen above the passions surrounding this case and produced a book of remarkable balance and restraint.

The heart of this study, and its most significant accomplishment, is the fullest evaluation ever attempted of the facts of the Rosenberg case. It is the result of an extraordinarily extensive and impressive piece of historical detective work, involving a search through widely scattered archives and interviews with dozens of surviving participants. But it is based above all on more than 200,000 pages of government documents released in the 1970s under the Freedom of Information Act. Defenders of the Rosenbergs (among whom both Radosh and Milton once numbered themselves) argued for years that these documents would provide proof of the couple's innocence. Instead, the records now leave virtually no doubt as to the Rosenbergs' guilt.

There is no "smoking gun" in this new material, no single, irrefutable piece of evidence capable of ending all debate. There is, rather, a vast accumulation of small but incriminating facts, an accumulation so large (and thus far so uncontradicted) that even the most determined conspiracy theorist will have difficulty believing that it could have been the result of a calculated frame-up. Out of this evidence, the authors arrive at a series of clear and seemingly irrefutable conclusions.

Among them: Julius Rosenberg was, in fact, the head of an amateurish but not ineffective spy ring. He did gain access, through his brother-in-law David Greenglass, to information about the American atomic bomb project and passed it along to the Russians (although it seems likely that the information was of relatively little value or importance). He also relayed information to the Soviets on other industrial and military projects, and he continued to coordinate his spy ring almost up to the moment of his arrest in 1950. Ethel Rosenberg was almost certainly his accomplice, although the concrete evidence against her was thin and largely circumstantial.

In the face of all this, the heroic image of the Rosenbergs as noble innocents, marching courageously to martyrs' deaths, becomes impossible to sustain. Nor is there much room for admiration for their principal supporters either. The Rosenbergs' lawyers, lionized by the left at the time, were stunningly inept and at times so concerned about their own (and their clients') ideological purity that they refused to explore promising avenues of defense. The American Communist Party was apparently more interested in the propaganda value of the case than in the fate of the defendants, and seemed content to let the Rosenbergs die because they would be of most use (and least danger) to the party as martyrs. The American Civil Liberties Union and its well- known counsel Morris Ernst became involved (belatedly) in the Rosenbergs' cause, but at the same time worked covertly with the FBI in an effort to elicit information from the prisoners.

But neither does this account bring much glory to the Rosenbergs' opponents, whose accusations may have been generally correct, but whose tactics were consistently questionable and at times shamefully unethical. Judge Irving Kaufman, who presided at the trial, "irretrievably compromised" himself even before the proceedings began by indicating to the prosecution his willingness to impose the death penalty on the defendants. His justification for this extraordinarily (and, Radosh and Milton believe, excessively) harsh sentence was, it appears, an ideological passion scarcely more attractive than that of the Rosenbergs themselves. Irving Saypol, the federal prosecutor, engaged in bludgeon-like and at times blatantly improper tactics that even an appeals court judge upholding the verdict later termed "totally reprehensible." J. Edgar Hoover and the FBI inflated what they knew to be a weak case against Ethel Rosenberg into a prosecution that led to her death largely, it seems, in the hope that her peril would serve as a "lever" to induce her husband to confess and inform.

The Rosenberg case is, in short, a story whose principal figures are not perhaps as villainous as their fiercest critics have at times claimed. But it is also a story with no heroes. "Partisans on both sides," the authors argue, "were convinced that they held a monopoly on truth and that the end justified the means." Julius and Ethel Rosenberg were, in the end, victims of dogmatism: their own and that of their opponents. They were not, it now seems clear, innocent martyrs. But they were indeed scapegoats, who paid with their lives for the passions and anxieties of an intensely ideological era.