WASHINGTON - A recent federal court ruling that favored Burroughs-Wellcome Co. against challenges to its AZT patents has clarified conditions under which the NIH may claim rights to a patent, but otherwise does not break new legal ground.

Barr Laboratories Inc. and Novopharm Inc. had argued that six U.S. patents for AZT held by Burroughs-Wellcome were invalid and could not be infringed by their generic versions of the drug because Burroughs-Wellcome failed to name NIH scientists as coinventors. As coinventor, NIH would have the right to license AZT to the generic manufacturers.