Therasense is now known as Abbott Diabetes Care. The case revolved around U.S. Patent No. 5,820,551, issued in 1998 for a disposable blood glucose test strip with an electrochemical sensor. Among prior art cited by Abbott was a patent issued to the company in 1985, No. 4,545,382, for a sensor consisting of an electrode with an enzyme bound to its external surface. The earlier patent included the following claim: “Optionally but preferably when being used on live blood, a protective membrane surrounds both the enzyme and the mediator layers, permeable to water and glucose molecules.”
That prior art was cited in numerous rejections of the application for the ‘551’ patent stretching back to 1984. But in 1997, Abbott’s then patent attorney Lawrence Pope and the company’s then R&D director Gordon Sanghera, Ph.D., argued that a person of skill in the art, when the ‘382’ patent was issued would have concluded the sensor disclosed there required the use of a membrane, in spite of the “optionally but preferably” wording.
Abbott also obtained a European counterpart to its earlier ‘382’ patent after overcoming an objection from the European Patent Office (EPO), which cited as prior art against Abbott a German reference requiring the use of a diffusion-limiting membrane. Abbott said its patent covered a protective rather than diffusion-limiting membrane and that the protective membrane was optional. Abbott did not, however, submit that to the USPTO when it pursued the ‘551’ patent.
Becton Dickinson sued Abbott in 2004, seeking a noninfringement judgment on two other patents that Abbott held for a blood glucose test strip. Abbott responded by countersuing Becton Dickinson as well as Bayer, Roche, and one of its suppliers Nova Biomedical for infringement of the two other patents as well as the ‘551’ patent. Roche settled on the eve of the trial, but the remaining co-defendants are still in the case.
Becton Dickinson, Nova Biomedical, and Bayer prevailed in both the district court and before a panel of federal circuit judges, with both courts citing Abbott’s failure to disclose the EPO argument. The latest federal circuit decision, which came on May 25, vacates the panel’s finding, and remands the case back to the district court, which is to reconsider the case based on intent to deceive and materiality.
The decision came about a year after a panel of federal circuit judges, which had upheld the original decision by Judge William H. Alsup of the U.S. District Court for the Northern District of California, then agreed to have the appeal reheard en banc to consider the issue of inequitable conduct.