The plea bargain earlier this month that freed nuclear scientist and alleged Los Alamos spy Wen Ho Lee induced jubilation among US scientific leaders. But last week's new disclosure that Lee made copies of the purloined computer tapes of nuclear data makes the accolades premature.

The US government first learned of the additional tapes during the final negotiations for Lee's plea bargain, in which 58 charges were dropped in favour of a guilty plea to a single count of mishandling secret documents. Lee has reportedly insisted they were destroyed. His attorneys only disclosed the copying of the tapes to surprised prosecutors when the plea bargain had been nearly struck, to ensure compliance with plea-bargain stipulations. But it was only uncovered publicly by Newsweek last week, setting off a new round of questions in the already troubling nuclear-secret débâcle.

The Los Alamos secrets case appears to engender hysteria like a nuclear chain reaction: in Congress first, stimulating federal prosecutors to react wildly, providing inaccurate testimony in the effort to convict Lee. And Lee's inhumane treatment during his nine months of incarceration could also be chalked up to that climate. Lee's release has also triggered harsh assessments of government witnesses.

The history of his treatment makes enthusiasm over Lee's release seem entirely justified. Weapons laboratory scientists have much to be proud of, not only for their science (see page 447), but also for so successfully maintaining a balance of scientific openness side by side with the fulfilment of tasks central to the United States' most sensitive defence interests. Yet it is clear from the Lee case that nuclear secrets weren't handled correctly.

The case shows, not for the first time, how scientists need to be ever more scrupulous in adhering to the rules. That is by far the best defence against misbegotten hysteria.