A multinational drugs company is trying to force a medical science journal to reveal the confidential statements made by the journal's expert reviewers in a test case that could undermine one of the central tenets of the scientific process.

Pfizer, the manufacturer of the anti-impotency drug Viagra, is trying to force the New England Journal of Medicine (NEJM) to release the names and comments of its anonymous peer reviewers who judged a dozen studies into two of the company's pain-killing drugs.

Pfizer has issued a subpoena demanding that the journal release the identities and comments of its referees, who normally remain anonymous so that they will feel free to give their honest opinions.

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A US district court judge is expected to rule this week on whether the drug company can force the NEJM to release the information, which some scientists claim would damage the confidential peer-review system that science uses to evaluate the merits of prepublication research.

Pfizer, which is based in New York, is being sued for damages allegedly caused by the drugs Celebrex and Bextra. Both pain killers belong to the same class of Cox-2 inhibitors as Vioxx, which was withdrawn in September 2004 because of fears that it had caused thousands of heart attacks and strokes. Although Bextra has been withdrawn, Celebrex is still on sale.

As part of its defence, Pfizer is seeking any additional information that may support its case. "Scientific journals such as NEJM may have received manuscripts that contain exonerating data for Celebrex and Bextra which would be relevant for Pfizer's causation defence," the company says in its motion.

But Donald Kennedy, the editor of the journal Science, said that this amounts to a fishing expedition. "If this motion succeeds, what journal will not then become an attractive target for a similar assault?" he wrote in a signed editorial. At stake is the public's interest in a fair system of evaluating and publishing scientific work.

The motion filed by Pfizer claims that the public has no interest in protecting the editorial process of a scientific journal.