The secretary of energy on Friday nullified a 1954 decision to revoke the security clearance of J. Robert Oppenheimer, a top government scientist who led the making of the atomic bomb in World War II but fell under suspicion of being a Soviet spy at the height of the McCarthy era.

In a statement, the energy secretary, Jennifer M. Granholm, said the decision of her predecessor agency, the Atomic Energy Commission, to bar Oppenheimer’s clearance was the result of a “flawed process” that violated its own regulations.

As time has passed, she added, “more evidence has come to light of the bias and unfairness of the process that Dr Oppenheimer was subjected to while the evidence of his loyalty and love of country have only been further affirmed”.

Historians, who have long lobbied for the reversal of the clearance revocation, praised the vacating order as a milestone. “I’m overwhelmed with emotion,” said Kai Bird, co-author with Martin J. Sherwin of American Prometheus, a 2005 biography of Oppenheimer that won the Pulitzer Prize.

“History matters and what was done to Oppenheimer in 1954 was a travesty, a black mark on the honour of the nation,” Bird said. “Students of American history will now be able to read the last chapter and see that what was done to Oppenheimer in that kangaroo court proceeding was not the last word.”

Christopher Nolan has a movie coming out on Oppenheimer that’s based on Bird and Sherwin’s book. A trailer for the film, named Oppenheimer, began playing on Thursday at movie theatres.

Alex Wellerstein, a historian of science at Stevens Institute of Technology in Hoboken, New Jersey, called the reversal long overdue.

“I’m sure it doesn’t go as far as Oppenheimer and his family would have wanted,” he said. “But it goes pretty far. The injustice done to Oppenheimer doesn’t get undone by this. But it’s nice to see some response and reconciliation even if it’s decades too late.”

New York Times News Service