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On August 02, 2017, the United States Court of Appealsfor the Federal Circuit ruled in favor of Applera Corp.and Tropix Inc.in the matter of Enzo Biochem Inc., Enzo Life Sciences Inc., Yale University v. Applera Corp., Tropix Inc. The Court affirmed that the district court accurately interpreted proper construction of claims in U.S. Patent No.5,449,767 (“the’767 patent”) and correctly analyzed Enzo’s doctrine of equivalents argument. In over thirteen years of litigation between the parties, the Court has considered this present infringement action on three separate occasions.
Technology as disclosed in the ‘767 patent pertains to use of nucleotide probes to detect presence of a particular DNA or RNA sequence in a sample or to identify anotherwise unknown DNA sequence. According to the ’767 patent, many procedures employed in biomedical research and recombinant DNA technology rely on use of radioactive labels such as isotopes of hydrogen, phosphorus, carbon, oriodine. The ’767patent also notes serious limitations and drawbacks pertaining to use of radioactive materials that include, elaborate safety precautions, expensive use and purchase, and short shelf-life. As an alternative to use of radioactive labels, the’767 patent elaborates on a series of novel nucleotide derivatives that contain biotin, iminobiotin, lipoic acid,and other determinants attached covalently to pyrimidine or purine ring. Further, the ’767 patent asserts that the use of modified detection approach provides detection capacities equal to or greater than procedures which utilize radio isotopes, and also overcomes other limitations and drawbacks pertaining to use of radioactive labels.
The disputed languageof claim 1 involves following limitation:
“wherein A comprises at least three carbon atoms and represents atleast one component of a signaling moiety capable ofproducing a detectable signal . . . .”
In 2004, Enzo filed a suitag ainst Applera alleging infringement of six patentsincluding the ’767 patent. After multiple years of litigation in 2012, an appeal to the federal court regarding invalidity issues decided on summary judgment, Enzo I, 599 F.3d 1325 (Fed.Cir.2010). The jury found Applera infringed the claims at issue and awarded $48.6million in damages. In appeal, Applera argued that the district court erred in its claim construction because claims of the ’767 patent only cover indirect detection and alternatively, if the claims cover direct detection, they are invalid for lack of written description andlack of enablement. The Federal Court agreed with Applera and reversed the district court’s claim construction, Enzo II, 780 F.3d 1149, 1150 (Fed. Cir. 2015). The Court concluded that the inventors were claiming only indirect detection and thus, held that “the district court erred in construingthe disputed claims of the patent-in-suit to cover bothdirect and indirect detection”. The Court then remanded the case to the district court to determine whether accused product infringes under proper claim construction. The district court agreed with Applera and rejected doctrine of equivalents argument raised by Enzo. Hence, Enzo Appealed.
Opinion of the Court
Firstly, the Court discussed scope of Enzo II and concluded that the district court correctly interpreted Enzo II. According to the Court, the district court rightly referred to specification of the ’767 patent and opined that specification does not support inclusion of direct detection.
Secondly, the Court discussed doctrine of equivalents. According to Enzo, Applera infringes claims under doctrine of equivalents and the district court “misconstrued” its expert declaration and improperly drew inferences in favor of Applera, rather than Enzo. Further, Enzo asserted that scope of equivalents focused on a particular subset of direct detection.
According to the Court, the district court rightly explained that the patent “describes its method of indirect detection as a superior means of detection as compared to direct detection, with ‘detection capacities equal to or greater than products which utilize’ direct detection”. The Court explained that “the specification provides additional support that claim 1 covers only indirect detection”.
The Court relied on Dolly, Inc. v. Spalding & Evenflo Cos., 16 F.3d 394, 400 (Fed. Cir. 1994), according to which “the concept of equivalency cannot embrace a structure that is specifically excluded from the scope of the claims” and noted that the same principle applies in the present case. “Including direct detection as an equivalent of indirect detection would render meaningless the claim language on which decision in Enzo II was based”. Thus, direct detection cannot be an equivalent of indirect detection in relation to these patent claims.
The doctrine of equivalents is generally considered when a product or process does not literally infringe a patented invention but the product or process contains elements identical or equivalent to each claimed element of the patented invention. Further, an analysis of role played by each element in context of function, way, and result of the claimed element and the product or process is required. In the present case, the court excluded direct detection from the scope of claims by referring to specification of the patent application even when the claims expressly did not exclude direct detection. Thus, the present case is an instance of difficulties pertaining to analysis of doctrine of equivalents and indicates proving doctrine of equivalents as unfeasible.