In Therasense, Inc. v. Becton, Dickinson & Co., the Court of Appeals for the Federal Circuit (CAFC) upheld a jury verdict of invalidity even though the district court had given erroneous jury instructions where the error was harmless because the claims were obvious. Therasense and Abbott Laboratories (Abbott) claimed that Becton, Dickinson & Company and Nova Biomedical Corp. (BD/Nova) infringed U.S. Patent No. 5,628,890 (the '890 patent), which claimed electrochemical sensors for measuring glucose levels in blood.

Abbott also accused BD/Nova of infringing U.S. Patents Nos. 5,820,551; 6,143,164; and 6,592,745. The district court found these three patents were invalid, unenforceable, or not infringed. These three patents were the subject of a separate appeal in Therasense, Inc. v. Becton, Dickinson & Co., Nos. 2008-1511, 1512, 1513, 1514, 1595 (Fed. Cir. Jan 25, 2010) in which the CAFC upheld the district court's finding that nearly all of the asserted claims were invalid and the '551 patent was unenforceable because of inequitable conduct.

The jury found that BD/Nova's BD Test strips infringed claims 11 and 12 of the '890 patent under the doctrine of equivalents. The jury also found that claims 11 and 12 were invalid, checking "Yes" in response to the questions, "Have defendants proven by clear and convincing evidence that Claims 11 and 12 of the '890 patent are invalid by reason of anticipation or obviousness?" and "Have defendants proven by clear and convincing evidence that Claims 11 and 12 of the '890 patent are invalid by reason of inadequate written description?" Abbott appealed the judgment that claims 11 and 12 are invalid. BD/Nova filed a cross-appeal with regard to finding of infringement under the doctrine of equivalents.

Abbott claimed the district court erred in its jury instruction that a reference anticipated a claim if it contained all of the elements of the claimed invention and those elements "could have been arranged as in the claimed invention" by those skilled in the art. Abbott argued that anticipation requires a single prior art reference to disclose exactly the same elements in exactly the same way as they are arranged in the claim. BD/Nova disagreed, arguing that a prior art reference may disclose each claim element either expressly or inherently. The CAFC agreed with Abbott, concluding that the district court's instruction incorrectly stated a prior art disclosure exists where the arrangement of individual claim elements were not actually described or depicted in the anticipatory reference. Instead, the CAFC stressed "the way in which the elements are arranged or combined" must be disclosed, since “anticipation requires the presence in a single prior art disclosure of all elements of a claimed invention arranged as in the claim.” With respect to BD/Nova's inherency argument, the CAFC noted that the jury instruction had not included inherency language, and that inherency required the prior art to necessarily include the unstated limitation, not that the prior art may or likely includes the limitation.

Once the CAFC determined that the jury instruction was erroneous, it next turned to whether the error had prejudiced the result. Because anticipation and obviousness were presented together in the same jury question, the error regarding anticipation would not be prejudicial if claims 11 and 12 would have been obvious as a matter of law, such that no reasonable jury could have returned a verdict that the claims are not obvious.

The CAFC held that claims 11 and 12 would have been obvious as a matter of law in light of the Nankai reference (U.S. Patent No. 5,120,420), one of the pieces of prior art asserted by BD/Nova. Two references, the Nankai and Ikeda references, were presented by BD/Nova in support of its obviousness argument. Abbott argued that the issue of whether the claims were obvious over the Nankai reference alone was not before the jury because this contention was not identified prior to trial. The CAFC disagreed, pointing out to claim charts submitted by BD/Nova that relied solely on the Nankai reference.

Nankai taught a sensor in which blood flowed into three channels, encountered on of three separate working electrodes, then reached a single shared counter-electrode. The strength of the electrical signal between the electrode and counter-electrode can be correlated to the level of glucose in the blood. Claims 11 and 12 of the '890 patent required only that a counter-electrode be placed downstream of an electrode. The CAFC determined the only difference between the claims and the Nankai reference was whether the aperture through which the blood entered was located on the top or side of the sensor. The CAFC held that the claims were obvious over the Nankai reference as a matter of law. Because it concluded a jury must have found the claims obviousness, it did not reach the questions of anticipation or inadequate written description.

BD/Nova had filed a cross-appeal on the issue of infringement under the doctrine of equivalents. Because the CAFC concluded that the asserted claims were invalid, whether BD/Nova infringed the claims would not affect its legal rights, the CAFC determined it lacked jurisdiction with respect to the cross-appeal. Alternatively, BD/Nova argued non-infringement as an alternate basis for affirming the district court's judgment. Because the CAFC concluded the claims were invalid as obvious, it declined to reach the question of infringement.