Therasense, Inc. v. Becton, Dickinson And Company

649 F.3d 1276 (2011)

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Nature of the Case

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Facts

The '551 patent involves disposable blood glucose test strips for diabetes management. The '551 patent claims a test strip with an electrochemical sensor for testing whole blood without a membrane over the electrode. In the prior art, some sensors employed diffusion-limiting membranes to control the flow of glucose to the electrode because the slower mediators of the time could not deal with a rapid influx of glucose. Other prior art sensors used protective membranes to prevent 'fouling.' Fouling occurs when red blood cells stick to the active electrode and interfere with electron transfer to the electrode. Protective membranes permit glucose molecules to pass, but not red blood cells. Abbott filed the original application in 1984. Over thirteen years, that original application saw multiple rejections for anticipation and obviousness, including repeated rejections over the '382 patent. The '382 patent specification discussed protective membranes in the following terms: '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.' In 1997, Abbott presented new claims to the examiner based on a new sensor that did not require a protective membrane for whole blood. The examiner requested an affidavit to show that the prior art required a membrane for whole blood at the time of the invention. Dr. Sanghera submitted a declaration to PTO stating: There is no teaching or suggestion of unprotected active electrodes for use with whole blood specimens in the '382 patent. Several years earlier, Abbott made representations to the European Patent Office (EPO) regarding the same 'optionally, but preferably' language in the European specification. '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.' P sued D seeking a declaratory judgment of noninfringement for the '164 and the '745 patents. P countersued alleging that P's strip infringed the '164, '745, and '551 patents. The district court granted summary judgment of non-infringement of all asserted claims in the '164 and '745 patents. The district court also found nearly all of the asserted claims of the '745 patent invalid due to anticipation. The district court determined that claims 1-4 of the '551 patent were invalid due to obviousness in light of the '382 patent and the '410 patent. The district court held the '551 patent unenforceable for inequitable conduct because P did not disclose to the PTO its briefs to the EPO filed on January 12, 1994, and May 23, 1995. A panel unanimously upheld the district court's judgments of noninfringement and invalidity. On unenforceability, the panel also affirmed, but with a dissent. The court granted P's petition for rehearing en banc.