The Great Chemical Divide: Federal Circuit Suggests the Insubstantial Differences Test for Evaluating Equivalence in Chemical Patent Cases

July, 14th, 2017

Categories: Articles, Blog Tags: CAFC, chemical, IPR, litigation, patent, precedential, PTAB, RCE, USPTO

By Mackenzie L. Long

In 1950 the Supreme Court outlined the two tests for evaluating the doctrine of equivalents in the case, Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605, 608-09 (1950). The first test is the function-way-result (“FWR”) test where the court determines whether the accused product performs substantially the same function in substantially the same way to obtain the same result. The second test is the insubstantial differences test where the court determines whether the accused product or process is substantially different from what is patented. Since Graver, there has been significant development in the case law relating to the doctrine of equivalents, however, there is no clear directive for which doctrine of equivalents test to apply. This lack of clarity has affected the consistency of results greatly and led to many unsound decisions, especially in the chemical arts.

On May 19, 2017 the Federal Circuit recommended that for infringement cases under the doctrine of equivalents, specifically cases involving chemical materials, the insubstantial differences test might be more fitting than the function-way-result test. Mylan Institutional LLC v. Aurobindo Pharma Ltd., 857 F.3d 858 (2017). In this case the Federal Circuit had to determine whether silver oxide was equivalent to manganese dioxide in making a dye used to map lymph nodes.

The Federal Court noted that one of the reasons why the FWR test does not work when dealing with chemical compositions is that these compositions possess many components which may not always make clear what their functions are or the way in which they perform. Also, the function and way prongs for chemical compounds may overlap and become vague. And “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.”

In reviewing the district court’s equivalence analysis, the Federal Circuit found that in applying the FWR test the district court either did not discuss the way prong of the test or it failed to apply it properly. While the district court may have correctly identified that the two reagents function the same way to produce the dye, the district court did not discuss the fact that manganese dioxide and silver oxide have different oxidation strengths or that manganese dioxide requires the use of an acid whereas the silver oxide does not or even that the two processes result in different yields. Therefore, the district court seemed to overlook the way prong of the FWR test.

The Federal Circuit then noted that the district court seemed to overlook the use of the insubstantial differences test also outlined in Graver, which in this case seemed to be the more appropriate choice given the set of facts. When the district court found that the two reagents were equivalent under the FWR test, the court failed to consider whether the two reagents were substantially different from one another, which in many regards they were substantially different.

The Federal Circuit concludes that the choice of equivalence test matters in this court and when the case returns to the district court for a full trial on the merits, the court should consider whether an evaluation of equivalence under the insubstantial differences test may be better suited to the particular facts of this case.

Practice Point:

Attorneys should be paying attention to this new understanding by the Federal Circuit in differentiating the doctrine of equivalents tests for mechanical and chemical related matters. Note that while the Federal Circuit is still allowing the district court to determine the test in this case (in a more thorough manner) attorneys should be prepared to show whether or not there is equivalence under both tests and more specifically the insubstantial differences test in regards to limitations involving the chemical arts.

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