The NAM sought to affirm a lower court decision limiting the ability of patent claimants to file "submarine" patents with claims that "surface" years later, when other companies have already developed substantial commercial interests without knowledge of the patent. The D.C. Circuit, however, overturned the lower court ruling on 6/5/00..In this case, the plaintiff claimed that several Microsoft software applications make unlawful use of his patented computer technology. Microsoft contended that the plaintiff failed to include an essential element of the invention as originally disclosed in the written description of the invention in a continuation application filed years later. The District Court agreed with Microsoft, holding that plaintiff's patents are invalid because they failed to meet a specific aspect of the written description requirement contained in the patent act.
In its brief, the NAM urged the appellate court to protect manufacturers from patentees who obtain claims that are broader than their disclosed invention. Manufacturers who invest hundreds of millions of dollars in technology are faced with the threat of "submarine patents", when an applicant intentionally delays the issuance of a patent, or drafts broad claims in order to extract favorable license terms from those who have already adopted and invested in the technology. The NAM asserted that the written description requirement, as applied in this case, may be the only defense available to manufacturers accused of infringement.