In Mylan v Aurobindo (May 19, 2017), the Federal Circuit first noted that “the appeal is unusual in a first sense in that it arises from the grant of a preliminary injunction based on the doctrine of equivalents. There are few such reported decisions . . . owing to the fact that equivalents cases are highly factual inquiries that rarely come clear on a premature record.”
The Federal Circuit then found that the district court, in its doctrine of equivalents analysis, “conducted an incomplete FWR [Function-Way-result] analysis while essentially bypassing the substantial differences test.” The district court failed to consider whether the key reagent in the process, manganese dioxide, was substantially different from the claimed reagent, silver oxide.
Below is the relevant portion of the decision:
Even if evaluating the “function” and “way” prongs is feasible, the FWR test may be less appropriate for evaluating equivalence in chemical compounds if it cannot capture substantial differences between a claimed and accused compound.
For example, consider the well-known compounds aspirin and ibuprofen, which chemists would not usually consider to be structural equivalents under the insubstantial differences test. Chemical compounds are characterized by their structures, and these two compounds differ substantially in structure (see appendix). However, the two compounds would seem to be substantial equivalents under the FWR test. They each provide analgesia and anti-inflammatory activity (“function”) by inhibiting prostaglandin synthesis (“way”) in order to alleviate pain, reduce fevers, and lessen inflammation (“result”). See, e.g., Hilton Davis Chem. Co. v. Warner-Jenkinson Co., 62 F.3d 1512, 1546 (Fed. Cir. 1995) (Lourie, J., dissenting). Thus, a compound may appear to be equivalent under the FWR test, but not under the substantiality of the differences test. Hence, the substantial differences test may be more suitable than FWR for determining equivalence in the chemical arts. Warner-Jenkinson, 520 U.S. at 40 (“Different linguistic frameworks may be more suitable to different cases, depending on their particular facts.”).
In this case, the district court conducted an incomplete FWR analysis while essentially bypassing the substantial differences test, in a situation where the latter test might seemingly be more appropriate. The claims in the process patents recite a method for preparing a specifically named compound by combining another specifically depicted compound with a third specific compound, viz., silver oxide. Each of these compounds is expressly named, and an infringement analysis must not take lightly the specific recitation of these materials. The district court found that the accused process using manganese dioxide was equivalent to the claimed process using silver oxide. But the court failed to consider whether the key reagent in the process, manganese dioxide, was substantially different from the claimed reagent, silver oxide, and hence whether the substitution for, and omission of, silver oxide left the accused infringer outside of the bounds of the claims. Manganese dioxide and silver oxide are substantially different in many respects. For example, manganese and silver are in different groups of the Periodic Table. In oxide form, manganese has an oxidation state of +4, while silver is +1. Those differences may well be relevant to equivalence at trial. Thus, the choice of test under the doctrine of equivalents may matter in this case.