The CAFC works through a chemical doctrine of equivalents case in Mylan v. Aurobindo

The first paragraph of Mylan v. Aurobindo:



Aurobindo Pharma Ltd., Aurobindo Pharma USA Inc.,
and Auromedics Pharma LLC (together, “Aurobindo”)
appeal from a decision of the United States District Court
for the Eastern District of Texas granting Mylan Institutional
LLC’s (“Mylan Inst.”) and Apicore US LLC’s
(“Apicore”) (together, “Mylan”) motion for a preliminary
injunction precluding Aurobindo from making, using,
selling, offering to sell, and importing the accused isosulfan
blue (“ISB”) product that allegedly infringes three of
Apicore’s patents—U.S. Patent 7,622,992 (“the ’992 patent”),
U.S. Patent 8,969,616 (“the ’616 patent”), and U.S.
Patent 9,353,050 (“the ’050 patent”). See Mylan Institutional
LLC v. Aurobindo Pharma Ltd., No. 2:16-cv-00491,
2017 WL 497593 (E.D. Tex. Feb. 7, 2017) (“Order Adopting
R&R”). Because the district court did not err in its
grant of the preliminary injunction under the ’050 patent,
although it did err in granting the injunction under the
’992 and ’616 patents, we affirm.


The relevant issue is the use of silver oxide as an oxidant:


Apicore owns, and Mylan Inst. is the exclusive licensee
of, the ’992, ’616, and ’050 patents, which relate to
ISB, a triarylmethane dye used to map lymph nodes. The
’992 and ’616 patents (together, “the process patents”) are
directed to a process for preparing ISB by reacting isoleuco
acid with silver oxide in a polar solvent, followed by
reaction with a sodium solution.


AND


Aurobindo acknowledged to the FDA that it was looking for a
reagent “other than silver oxide.” It eventually selected manganese diox-
ide, and its process resulted in ISB with a 5–10% impurity
which could not be removed by recrystallization.
Instead, it used preparatory HPLC to achieve an ISB
purity of greater than 99.5%. Mylan sued Aurobindo for
infringement and sought a preliminary injunction, which
the district court granted.


One issue


We first consider whether the district court erred in
finding that Mylan is likely to succeed on the merits
because Aurobindo “more likely than not” infringes the
process patents under the doctrine of equivalents. Report
and Recommendation, 2016 WL 7587325, at *12. To
establish a likelihood of success on the merits, a patentee
must show that it will likely prove infringement of the
asserted claims and that its infringement claim will likely
withstand the alleged infringer’s challenges to patent
validity and enforceability. Sciele Pharma, Inc. v. Lupin
Ltd., 684 F.3d 1253, 1259 (Fed. Cir. 2012) (citing Amazon.com,
239 F.3d at 1350). A preliminary injunction
should not issue if the accused infringer “raises a substantial
question concerning either infringement or validity.”
Amazon.com, 239 F.3d at 1350.



The position of the accused infringer Aurobindo:



Aurobindo argues that it had raised a substantial
question of infringement of the process patents under the
doctrine of equivalents because manganese dioxide oxidizes
isoleuco acid in a different way than silver oxide in
that manganese dioxide is a strong oxidizing agent,
whereas silver oxide is a weak oxidizing agent. Additionally,
Aurobindo continues, manganese dioxide oxidation
requires the use of an acid and the patents specifically
report the use of silver oxide as not requiring an acid.


The counter:


Mylan responds that the district court correctly found
a likelihood of success on the merits of infringement
under the doctrine of equivalents because the court
properly found that manganese dioxide and silver oxide
are equivalent in the context of the process patents.
Specifically, the court credited Sessler’s testimony in light
of record evidence that the silver oxide and manganese
dioxide processes produce crude ISB in similar yields.
The court explained that if manganese dioxide was a
substantially stronger oxidizing agent than silver oxide, a
skilled artisan “would expect different results.”


The CAFC noted:



As set forth below, we conclude that the district
court’s analysis of equivalence in this case was flawed, no
doubt because of the sparse and confusing case law concerning
equivalents, particularly the paucity of chemical
equivalence case law, and the difficulty of applying the
legal concepts to the facts. We will attempt to provide
more clarity on these subjects.
(...)
Moreover, the law on the doctrine of
equivalents as applied to chemical materials is not clear,
and its misapplication can lead to unsound results. This
appears to be such a case.


Yes, the CAFC does mention Graver Tank.

The CAFC considered the district court to err in its analysis
of the "way" the chemicals acted:


The district court correctly evaluated the “function”
aspect of the FWR test—deciding, in effect, that the
function of the silver oxide was to oxidize the precursor
isoleuco compound to ISB acid.6 But that is not considering
the “way” the oxidation works. Manganese dioxide
and silver oxide may have the same function, but the
question is whether they operate in the same way. Critical
facts that might be considered in an equivalents
analysis include the relative oxidation strengths of the
two oxidizing agents, as argued by Aurobindo, and the
fact that manganese dioxide requires the use of an acid
for oxidation, but silver dioxide does not, and results in a
different yield. All of this in fact may at trial indicate a
different “way.” Thus, there is room for sufficient doubt
as to whether silver oxide and manganese dioxide oxidize
isoleuco acid in the same way so as to satisfy the “way”
prong of the FWR test.

Accordingly, the district court erred in its equivalents
analysis under FWR and we reverse its determination.



Of interest to practitioners in the chemical arts AND to
chemists:


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.”).
(...)
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.


The CAFC's mention of Graver Tank was brief. In Graver, the
patentee claimed alkaline earth silicates, which encompass magnesium.
The infringer was using manganese silicates.

The dissent of Justice Douglas was short, and likely the correct
analysis:


The Court applies the doctrine of equivalents in a way which subverts the constitutional
and statutory scheme for the grant and use of patents.

The claims of the patent are limited to a flux "containing a major proportion of alkaline earth metal silicate."
Manganese silicate, the flux which is held to infringe, is not an alkaline earth metal silicate.
It was disclosed in the application and then excluded from the claims.
It therefore became public property. See Mahn v. Harwood, 112 U. S. 354, 112 U. S. 361.
It was, to be sure, mentioned in the specifications.
But the measure of the grant is to be found in the claims,
not in the specifications. Milcor Steel Co. v. Fuller Co.,
316 U. S. 143, 316 U. S. 145-146. The specifications can be used to limit,
but never to expand, the claim. See McClain v. Ortmayer, 141 U. S. 419, 141 U. S. 424.

The Court now allows the doctrine of equivalents to erase those time-honored rules. Moreover, a doctrine which is said to protect against practicing "a fraud on a patent" is used to extend a patent to a composition which could not be patented. For manganese silicate had been covered by prior patents, now expired. Thus, we end with a strange anomaly: a monopoly is obtained on an unpatented and unpatentable article.