Document ID: s3://data.kl3m.ai/documents/govinfo/USCOURTS/USCOURTS-ca13-20-01098/USCOURTS-ca13-20-01098-0/pdf.json

Parties Involved:
Allergan Sales, LLC
Not party
Allergan USA, Inc.
Not party
Allergan, Inc.
Not party
Seymour H. Fein
Not party
Ferring B.V.
Appellant
Ferring International Center SA
Appellant
Ferring Pharmaceuticals Inc.
Appellant
Ronald V. Nardi
Not party
Reprise Biopharmaceutics, LLC
Appellee
Serenity Pharmaceuticals Corporation
Appellee
Serenity Pharmaceuticals, LLC
Appellee

Document Text:

United States Court of Appeals 

for the Federal Circuit ______________________

FERRING B.V., FERRING INTERNATIONAL 

CENTER SA, FERRING PHARMACEUTICALS INC.,

Plaintiffs-Appellants

v.

ALLERGAN, INC., ALLERGAN USA, INC., 

ALLERGAN SALES, LLC, SEYMOUR H. FEIN, 

RONALD V. NARDI,

Defendants

SERENITY PHARMACEUTICALS CORPORATION, 

SERENITY PHARMACEUTICALS, LLC, REPRISE 

BIOPHARMACEUTICS, LLC,

Defendants-Appellees

______________________

2020-1098

______________________

Appeal from the United States District Court for the 

Southern District of New York in No. 1:12-cv-02650-PKC, 

Senior Judge P. Kevin Castel.

______________________

Decided: November 10, 2020

______________________

MARY W. BOURKE, Womble Bond Dickinson (US) LLP, 

Wilmington, DE, argued for plaintiffs-appellants. Also represented by KRISTEN HEALEY CRAMER, DANA KATHRYN 

SEVERANCE; JOHN W. COX, JOSHUA A. DAVIS, Atlanta, GA.

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2 FERRING B.V. v. ALLERGAN, INC.

 SARAH ELIZABETH SPIRES, Skiermont Derby LLP, Dallas, TX, argued for defendants-appellees. Also represented 

by PAUL SKIERMONT.

 ______________________

Before O’MALLEY, REYNA, and CHEN, Circuit Judges.

O’MALLEY, Circuit Judge.

When a district court enters judgment at the summary 

judgment stage, it is at times difficult to discern on appeal 

whether the nonmovant failed to raise sufficient factual 

disputes to prevent judgment or the court acted despite 

such disputes. Where the matter adjudged is a quintessentially fact-laden one, such as the equitable matter at issue 

here, it is especially important that we guard against a 

rush to judgment. We conclude that such a rush to judgment happened here. Accordingly, we vacate and remand

for further development of the record and a later-stage resolution of whether Appellants are equitably estopped from 

seeking to correct inventorship of the patents at issue in 

these proceedings.

BACKGROUND

I

Seymour Fein worked as a consultant for Ferring Pharmaceuticals Inc. from December 1998 until the company

terminated his consulting agreement on November 7, 2002. 

While Fein was consulting for Ferring Pharmaceuticals 

Inc., he became involved in a Ferring1 project involving 

desmopressin. Desmopressin is a synthetic analog of the 

naturally occurring hormone arginine vasopressin, which 

1 We refer collectively to Appellants Ferring B.V., 

Ferring International Center SA, and Ferring Pharmaceuticals Inc. collectively as “Ferring.”

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regulates the body’s retention of water. Among other 

things, desmopressin is used to treat nocturia (disruption 

of nighttime sleep due to the need to urinate). 

As early as 1999, Ferring scientists Jens Peter 

Nørgaard and Thomas Senderovitz were involved in a clinical trial studying the bioavailability and pharmacokinetics of desmopressin. The trial demonstrated that orally 

administered desmopressin had a duration of action in the 

range of six hours. A 2000 presentation authored by 

Nørgaard acknowledged low bioavailability and high variation of absorption as known problems with using desmopressin to treat nocturia, hypothesized that “[t]he need for 

high plasma levels of desmopressin” to achieve an antidiuretic effect “is overestimated,” and suggested that increased desmopressin doses may pose a safety issue. 

S.A. 4431–32, 4435, 4455.2 Ferring initiated a follow-on 

study in October 2000, shepherded by Nørgaard and

Senderovitz, to model the desmopressin dose-response relationship. The results of the follow-on study supported 

their hypothesis that low doses and plasma concentrations 

of desmopressin could be clinically effective. 

As Fein recalls events, Ronald V. Nardi, a Ferring employee, approached him in 2001 seeking assistance with a 

Ferring project involving clinical studies using a desmopressin oral tablet to treat adult nocturia. Nardi sought 

ideas from Fein regarding how to minimize the high incidence of hyponatremia Ferring had observed in its clinical 

trials. Hyponatremia is a condition in which sodium levels 

in the blood fall to abnormally low levels, and can lead to 

seizures, cardiac arrhythmias, cerebral edema, and death. 

Fein recounts that, in August 2001, he suggested to Nardi 

2 “S.A.” refers to the corrected supplemental appendix filed by the parties on September 17, 2020. Corrected 

Supplemental Appendix, Ferring B.V. v. Allergan, Inc., 

No. 20-1098 (Fed. Cir. Sept. 17, 2020), ECF No. 39.

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that hyponatremia could be reduced or avoided by using 

lower dosages of desmopressin than Ferring had previously 

tested, and that such dosages could be administered in a 

waterless orodispersible form (a “melt”) sublingually 

through the mucosal membranes of the mouth to improve 

bioavailability of the desmopressin. 

In March 2002, Nørgaard and Senderovitz began designing additional clinical studies to test a new orodispersible form of desmopressin known within Ferring as 

“NEWMIN.” By then, a study comparing NEWMIN to Ferring’s previously marketed tablet had demonstrated that 

the bioavailability of NEWMIN was approximately double 

that of the previously marketed tablet. NEWMIN’s increased bioavailability “open[ed] up the possibility of studying lower doses of desmopressin than currently 

marketed.” J.A. 3632. By April 2002, Ferring had designed a clinical study protocol, sponsored by Senderovitz 

and designated CS007. CS007 would investigate the pharmacokinetics and antidiuretic effect of orodispersible 

desmopressin tablets containing five low doses of desmopressin alongside a placebo. 

In May 2002, Ferring filed Great Britain Patent Application No. GB0210397.6 covering various dosage forms of 

an orodispersible desmopressin formulation. Ferring’s application includes a claim directed to “[a] pharmaceutical 

dosage form of desmopressin adapted for sublingual absorption.” J.A. 286. The application does not list any inventors. 

When Ferring experienced delays in production of the 

orodispersible tablets to be used in its CS007 study, 

Nørgaard and Senderovitz planned another clinical study 

to investigate the pharmacokinetic and antidiuretic effects

of various low desmopressin doses. The study was designated CS009 and used an intravenous desmopressin formulation to approximate the CS007 orodispersible doses. 

Fein did not participate in the design of the CS009 clinical 

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study protocol. In June 2002, Fein was selected to oversee 

United States operations of CS009. As part of that role, 

Fein received via email a copy of Ferring’s CS009 clinical 

study protocol. J.A. 3741. After reviewing the protocol, 

Fein suggested certain changes, including converting the 

original dose levels (expressed in nanograms) to doses on a 

per-weight basis (nanograms per kilogram) to accommodate study participants within a greater weight range. 

In September 2002, Ferring filed Application 

No. PCT/IB02/04036 under the Patent Cooperation Treaty 

(“PCT”), claiming priority from Ferring’s Great Britain application. Ferring’s PCT application lists six inventors, including Senderovitz, Fein, and Nardi. Fein and Nardi were 

included as inventors based on Nardi’s representation that 

they had conceived the sublingual route of administration. 

Two months later, Ferring terminated Fein’s consulting 

agreement. 

II

From November 21, 2002 to December 14, 2004, Fein’s 

attorney, William Speranza, corresponded with Ferring regarding Fein’s purportedly inventive contribution of the 

sublingual administration route. We refer to the letters 

and emails exchanged between Ferring and Speranza collectively as “the Speranza correspondence.”

A letter from Speranza dated November 21, 2002 asserted that Fein invented material included in Ferring’s 

PCT application, characterizing Fein’s contribution as “a 

sublingual, transmucosal route of delivery which affords a 

number of advantages . . . including enabling the effective 

use of formulations having reduced concentrations of 

desmopressin.” J.A. 531. The letter asserted that Fein had 

no obligation to assign to Ferring any rights in inventions 

Fein conceived while consulting for Ferring. Consequently, 

Fein would have ownership rights in any patents that may 

issue from Ferring’s PCT application. Speranza requested 

that Ferring provide copies of all prosecution documents 

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and any documents filed in subsequent national phase applications. Ferring and Speranza then exchanged several 

letters regarding the events underlying Fein’s contribution. In January 2003, Speranza sent Ferring another letter reiterating Fein’s “ownership rights in the invention, 

the pending application therefor and any patents that may 

issue on his invention.” J.A. 534. The letter renewed

Speranza’s request that Fein “be kept fully apprised” of the 

status of Ferring’s PCT application. Id. Speranza also 

raised the possibility that “it may be necessary for [Fein] to 

take steps independent of Ferring as may be necessary to 

protect his interests.” J.A. 534–35.

Ferring responded on April 9, 2003, advising Speranza 

that it had “now taken the decision to drop the feature 

‘adapted for sublingual administration.’” J.A. 537. Considering the prior art, Ferring found it “clear . . . that the feature does not in this context confer a delimitation i.e. 

novelty.” Id. Accordingly, Ferring relayed that Fein would

“not be one of the designated inventors in the modified PCT 

application to be filed.” Id.

Approximately one week later, on April 17, Speranza 

sent an email to Ferring stating that Fein “ha[d] no fundamental problem with” Ferring’s decision to omit “the feature of sub-lingual administration invented by Dr. Fein.” 

J.A. 539. Speranza stated that “Fein also is the inventor of 

the associated low dosage possibilities enabled by the sublingual administration route,” expressed Fein’s understanding that this was not “specifically claimed in the UK 

application,” and noted his “assum[ption] that Ferring is 

not pursuing that subject matter in the planned PCT filing.” Id. The email also informed Ferring that “Fein is 

planning to himself proceed with pursuing patent protection covering the sub-lingual administration route and the 

associated low dosage possibilities enabled by same which 

he invented, all at his own expense going forward and with 

the understanding that Ferring relinquishes any ownership claims thereto.” Id. Finally, Speranza notified 

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FERRING B.V. v. ALLERGAN, INC. 7

Ferring that Fein “plans to claim priority to [Ferring’s] UK 

application,” and requested that Ferring provide “the particulars of the UK filing.” Id.

On April 29, 2003, Ferring responded, explaining that 

it would not pursue patent protection for the invention described by Speranza in his April 17 letter, because “[t]he 

low dosage possibilities enabled by the sublingual administration route are already available in the public domain.” 

J.A. 542. Ferring noted, however, that it “cannot of course 

say now that Ferring will not make any claim as to ownership of any other material Dr[.] Fein may include in any 

patent application . . . without seeing the text.” Id. Without “knowing what claims for novelty or inventive steps 

[Fein] ha[d] in mind,” Ferring cautioned that it “cannot be 

sure that [Fein’s forthcoming application] does not cover 

matters to which employees of the Ferring Group have contributed or regarding which Dr[.] Fein is bound to [Ferring] 

by terms of confidentiality.” Id. Ferring provided Fein 

with the filing date and application number for its Great 

Britain application, but refused to provide Fein with a copy 

of the application, asserting that “Fein has no entitlement 

to the patentable subject matter disclosed therein.” Id.

On May 6, 2003, Fein filed Application 

No. PCT/US2003/014463, claiming priority from Ferring’s 

Great Britain application and listing Fein as the sole inventor. Fein’s application claims low-dose pharmaceutical 

compositions comprising desmopressin and methods of 

treating various conditions with such compositions. 

Though some of Fein’s PCT application claims recite

desmopressin formulations adapted for various routes of 

administration, none of his PCT application claims are limited to desmopressin formulations administered sublingually. 

The next day, Ferring filed a modified PCT application, 

which was assigned Application No. PCT/IB03/02368. Ferring’s modified application claims priority from Ferring’s 

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Great Britain application and Ferring’s September 2002 

PCT application and does not list Fein as an inventor or 

contain claims directed to sublingual administration of 

desmopressin. Ferring ultimately obtained U.S. Patent 

Nos. 7,569,429 (“the ’429 patent”) and 7,947,654 (“the ’654 

patent”) claiming priority from its Great Britain application. 

During 2003 and 2004, Fein conducted clinical studies 

related to low-dose desmopressin. Relevant here, in August 2003, Fein initiated a study designated CNF Desmo 

PK200301, titled “A Cross-Over Study Investigating the 

Antidiuretic Effects and Pharmacokinetics of Three Low 

Doses of Desmopressin Administered via Intravenous Infusion for 2 Hours in Over-Hydrated Healthy Non-Smoking 

Male and Female Volunteers.” J.A. 653. Fein’s CNF 

Desmo PK200301 used substantially the same protocol as 

Ferring’s CS009 clinical study. Compare J.A. 3823–26,

with J.A. 4153–56. 

On November 12, 2003, Fein filed U.S. Patent Application No. 10/706,100 (“the ’100 application”) as a continuation-in-part of his May 2003 PCT application. Like Fein’s 

PCT application, the ’100 application claims low-dose pharmaceutical compositions comprising desmopressin and 

methods of treating various conditions with such compositions. J.A. 651. None of the ’100 application claims are

limited to desmopressin formulations administered sublingually. Id. Fein’s May 2003 PCT application published on 

May 21, 2004. His ’100 application published approximately two months later on July 15, and ultimately issued 

on September 21, 2010 as U.S. Patent No. 7,799,761 (“the 

’761 patent”). The ’761 patent claims recite pharmaceutical compositions comprising varying low doses of desmopressin administered by various routes of delivery. Some 

dependent claims further require that the claimed desmopressin doses establish a particular desmopressin 

plasma/serum concentration range, or that that a particular desmopressin plasma/serum concentration range be 

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FERRING B.V. v. ALLERGAN, INC. 9

maintained for a specified duration. None of the claims recite pharmaceutical compositions limited to sublingual administration.

On December 9, 2004, Ferring sent Speranza a letter 

advising Speranza that Ferring was “truly surprised” that 

Fein had proceeded with his May 2003 PCT application, 

which “contain[s] an invention to which we believe he has 

no entitlement and which in particular discloses information confidential and proprietary to Ferring.” J.A. 544. 

Ferring’s letter notified Speranza that it would “take all 

necessary steps to protect its rights and interests but before taking formal legal action [Ferring] wish[ed] to give 

[Fein] an opportunity to explain himself.” Id. Ferring further informed Speranza that if it “d[id] not receive a full 

and satisfactory explanation within 14 days of this letter 

[Ferring] will commence formal action.” Id.

Speranza responded five days later, sending Ferring

two letters on December 14. The first letter reminded Ferring that it had acknowledged Fein’s intent to proceed with 

his own patent application. Speranza also posited three 

possible reasons for Ferring’s assertion that Fein had “no 

entitlement” to the invention in his published PCT application. First, and “as would appear” from Ferring’s December 9 letter, Fein’s PCT “application ‘discloses information 

confidential and proprietary to Ferring.’” J.A. 546. Second, Ferring believes “that this low dosage invention of 

Dr. Fein is simply not patentable because of prior art.” Id. 

Third, “Fein is not the inventor of the claimed low dose invention and/or . . . Fein cannot assert ownership rights to 

it.” Id. Speranza expressed his opinion that “[o]ur dealings 

and communications throughout 2003 made clear that Ferring made no claim to low dosage desmopressin as its invention.” J.A. 546–47. Despite the earlier communications 

regarding claims involving the sublingual route of delivery, 

Speranza made no mention of the use of a sublingual route 

for the delivery of low dosages. To the extent Ferring’s allegation referred to misuse of confidential information,

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10 FERRING B.V. v. ALLERGAN, INC.

Speranza explained that “[w]hatever Ferring data is set 

forth in Dr. Fein’s subject patent application comes solely 

from the text of the UK priority application filed by Ferring 

in May 2002, naming Dr. Fein as a co-inventor.” J.A. 547. 

In closing, Speranza stated that he “trust[ed] this response 

will put this matter to rest.” Id. “[I]n view of the fact that 

Ferring itself published over a year ago the allegedly ‘confidential and proprietary’ information to which [Ferring’s] 

letter refers,” Speranza deemed it “irresponsible for Ferring to level such serious accusations at Dr. Fein and to 

threaten immediate legal action based thereon.” Id.

Speranza’s second December 14, 2004, letter to Ferring 

focused on Ferring’s allegations of misuse of confidential 

information. It acknowledged Ferring’s “apparent concern 

with the content of Dr. Fein’s published applications” and 

informed Ferring that Fein filed a continuation-in-part 

U.S. patent application (i.e., the ’100 application) “which 

has since published as U.S. Patent Application Publication 

No. 2004/0138098, dated July 15, 2004, also directed to low 

dose desmopressin.” J.A. 550. Speranza’s letter stated 

that a copy of the ’100 application was included as an attachment, but Ferring disputes that it ever received a copy

of the ’100 application. Referencing Example 8 and Figures 

1–9 of the ’100 application, Speranza’s letter noted that the 

’100 application “contains data beyond that included in the 

original Ferring UK application,” which data “did not emanate from Ferring.” J.A. 551. This letter was Speranza’s 

last communication with Ferring before Ferring filed suit 

in April 2012.

With his patent applications pending, Fein took steps 

to commercialize his invention. In 2006, Fein and Samuel 

Herschkowitz formed Serenity Pharmaceuticals Corporation and Serenity Pharmaceuticals, LLC to raise funds to 

cover the prosecution of Fein’s patents and pursue clinical 

development. In late 2006, Fein founded Reprise Biopharmaceutics, LLC, a holding company having five members. 

Fein transferred to Reprise his intellectual property rights 

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FERRING B.V. v. ALLERGAN, INC. 11

related to his claimed desmopressin invention. We refer to 

Reprise, Serenity Pharmaceuticals Corporation, and Serenity Pharmaceuticals, LLC collectively as “Serenity.”

In May 2007, Fein filed U.S. Patent Application 

No. 11/744,615 (“the ’615 application”) as a divisional of the 

’100 application. The ’615 application published on November 15, 2007 and matured into U.S. Patent No. 7,405,203

(“the ’203 patent”) on July 29, 2008. The ’203 patent claims 

recite methods of administering low doses of desmopressin 

by various routes of delivery to establish various desmopressin plasma/serum concentration ranges. Some claims 

further require that the plasma/serum concentration range 

be maintained for a specified duration. None of the claims 

recite sublingual administration of desmopressin. 

In July 2008, Fein filed U.S. Patent Application 

No. 12/173,074 (“the ’074 application”) as a continuation of 

the ’615 application. The ’074 application published on 

January 1, 2009 and issued as U.S. Patent No. 7,579,321

(“the ’321 patent”) on August 25, 2009. The independent 

claims of the ’321 patent recite methods of administering 

low doses of desmopressin by various routes of delivery to 

produce an antidiuretic effect or a particular urine osmolality in a patient. Several claims of the ’321 patent further 

require that the urine osmolality or antidiuretic effect be 

maintained for a specified duration. Again, none of the 

claims recite sublingual administration of desmopressin. 

We refer to the ’203 patent, ’761 patent, and ’321 patent

collectively as “the Fein patents.”

By the end of 2008, Fein had conducted Phase I and 

Phase II clinical studies of a low-dose desmopressin intranasal spray adapted for transmucosal delivery. Fein

proceeded with Phase III clinical trials in 2009 and 2010. 

On March 31, 2010, Serenity Pharmaceuticals, LLC and 

Reprise entered into agreements with Allergan Sales, LLC, 

Allergan USA, Inc., and Allergan, Inc. (collectively, “Allergan”) to develop and commercialize a low-dose 

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desmopressin intranasal spray, assigning all of their 

desmopressin intellectual property rights to Allergan. As 

part of the agreements, Reprise and Serenity Pharmaceuticals, LLC warranted that there was no threat of litigation 

from any third party regarding the Fein patents. Allergan 

made a $43 million up-front payment to acquire the desmopressin intellectual property rights. 

On October 12, 2010, Ferring’s counsel filed a request 

for reexamination of Fein’s ’203 patent, arguing that the 

prior art rendered the independent claims anticipated or 

obvious. The U.S. Patent and Trademark Office (“USPTO”) 

rejected Ferring’s request for reexamination of the ’203 patent on January 19, 2011. 

III

On April 5, 2012, Ferring filed a complaint in district 

court asserting New York state law claims and claims for 

correction of inventorship of the Fein patents under 

35 U.S.C. § 256. The matter was assigned to District Judge 

Robert Sweet. The complaint named Allergan, Serenity, 

Fein, and Nardi as defendants (collectively, “Defendants”). 

Ferring alleged that Ferring scientists Nørgaard and 

Senderovitz should be substituted for Fein as the sole inventors, or at least added as co-inventors, to the Fein patents. Ferring filed an amended complaint in August 2013. 

Defendants answered Ferring’s amended complaint. Allergan filed counterclaims to correct inventorship of Ferring’s 

’429 and ’654 patents (which issued from Ferring’s modified PCT application), claiming that Fein should be named 

as the sole inventor or as a joint inventor on those patents. 

In April 2015, Allergan moved for summary judgment 

that Ferring’s § 256 claims were barred by equitable estoppel, and the non-Allergan defendants joined in Allergan’s 

motion. Several months later, in September 2015, the district court granted Allergan’s motion for summary judgment and dismissed Ferring’s § 256 claims. 

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In considering Allergan’s summary judgment motion, 

the district court decided as a threshold matter that conduct occurring before the issuance of the Fein patents could 

give rise to equitable estoppel of Ferring’s claims for correction of inventorship. The district court then concluded

that Ferring’s inaction for over seven years following

Speranza’s December 2004 letters satisfied the misleading 

conduct prong of equitable estoppel. When Ferring was 

faced with Speranza’s reference “to ‘low dosage’ applications of desmopressin as Fein’s inventions,” the district 

court reasoned, Ferring’s response “was not that the lowdosage invention was Ferring’s intellectual property, but 

that it was not patentable at all, and that Ferring would no 

longer be pursuing claims directed toward it.” Ferring B.V. 

v. Allergan, Inc., 253 F. Supp. 3d 708, 718 (S.D.N.Y. 2015).

The district court found Ferring’s threat of “immediate legal action with respect to [Fein’s PCT] application” misleading, because “Ferring did not disagree or otherwise 

challenge Mr. Speranza’s assertion that low dosage development was Fein’s intellectual property,” despite the fact 

that “Ferring was aware of two Fein patent applications 

that include claims for low desmopressin doses and low 

desmopressin plasma concentration levels.” Id. Therefore, 

the district court concluded, “Ferring’s present application 

to correct inventorship contradicts its earlier position in 

the Speranza correspondence.” Id. The district court also 

concluded that the reliance and prejudice prongs of equitable estoppel were satisfied. 

In June 2016, the district court denied Ferring’s motion 

for a stay and for certification of judgment to allow Ferring 

to appeal the equitable estoppel summary judgment ruling. 

The non-Allergan defendants subsequently moved to be 

substituted for Allergan as counterclaim plaintiffs, and the 

district court granted that motion on September 14, 2017. 

Following Judge Sweet’s passing, the action was reassigned to District Judge P. Kevin Castel, who refused to 

reconsider Judge Sweet’s earlier rulings and proceeded to 

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address the counterclaims for correction of inventorship of 

Ferring’s ’429 and ’654 patents. Following a bench trial on 

those counterclaims, the district court entered judgment in 

favor of Ferring, refusing to add Fein to Ferring’s ’429 or 

’654 patents as either the sole or a joint inventor. Final 

judgment in this matter was entered on September 30, 

2019.3 

Ferring appeals the district court’s September 2015 equitable estoppel decision. Serenity also appealed

Judge Castel’s September 2019 judgment on its counterclaims, and we consolidated Ferring’s appeal with 

3 Ferring points out that, at least as to Fein’s claim 

of co-inventorship of Ferring’s ’429 and ’654 patents, 

Judge Castel found Dr. Fein’s testimony not credible. Ferring B.V. v. Allergan, Inc., No. 12-cv-2650, 2019 WL 

6183501, at *11 (S.D.N.Y. Sept. 27, 2019). In the form of a 

supplemental letter pursuant to Federal Rule of Appellate 

Procedure 28(j), Ferring also brought to our attention that 

another district court judge, Chief Judge Colleen 

McMahon, also questioned Fein’s credibility regarding his 

involvement with low-dose desmopressin formulations. 

Ferring Pharm. Inc. v. Serenity Pharm., LLC, 

No. 17-cv-09922, 2020 WL 4926458, at *63 (S.D.N.Y. 

Aug. 21, 2020) (concluding, after bench trial in parallel proceeding involving the validity of the ’203 and ’321 patents 

under 35 U.S.C. § 102(f), that “[c]ontrary to his absolutely 

incredible testimony, Dr. Fein did not suggest the idea of a 

‘low dose that is enabled [by sublingual administration]’ . . . to Dr. Norgaard and his colleagues at Ferring” 

(second alteration in original) (citation omitted)). 

While Fein has not moved to strike those references 

and the conclusions reached by those judicial officers on 

differently developed records, we must base our judgment 

on what was—and was not—presented to Judge Sweet during the summary judgment proceedings at issue here. 

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FERRING B.V. v. ALLERGAN, INC. 15

Serenity’s appeal. We subsequently granted Serenity’s motion to dismiss its appeal, leaving Ferring’s appeal as the 

only pending appeal. We have jurisdiction pursuant to 

28 U.S.C. § 1295(a)(1).

DISCUSSION

On appeal, Ferring argues that the district court erred 

by: considering conduct that preceded the issuance of the 

Fein patents in the equitable estoppel analysis; resolving 

disputed issues of fact in favor of Defendants; and ignoring 

evidence of Defendants’ unclean hands. We address each 

argument in turn. 

I

Our review of a district court’s grant of summary judgment of equitable estoppel proceeds in two steps. John 

Bean Techs. Corp. v. Morris & Assocs., Inc., 887 F.3d 1322, 

1327 (Fed. Cir. 2018) (citing Scholle Corp. v. Blackhawk 

Molding Co., 133 F.3d 1469, 1471 (Fed. Cir. 1998)). First, 

applying the law of the regional circuit (here, the Second 

Circuit), we review whether there are genuine issues of material fact. See Accenture Global Servs., GmbH v. Guidewire Software, Inc., 728 F.3d 1336, 1340 (Fed. Cir. 2013) 

(citing Teva Pharm. Indus. v. AstraZeneca Pharm. LP, 

661 F.3d 1378, 1381 (Fed. Cir. 2011)); Fed. R. Civ. P. 56(a). 

The Second Circuit reviews a grant of summary judgment 

de novo, construing the evidence in the light most favorable 

to the nonmoving party and drawing all reasonable inferences in that party’s favor. Kuebel v. Black & Decker Inc., 

643 F.3d 352, 358 (2d Cir. 2011) (citation omitted). “Second, we review the district court’s application of equitable 

estoppel for abuse of discretion.” John Bean, 887 F.3d 

at 1327 (citing Radio Sys. Corp. v. Lalor, 709 F.3d 1124, 

1130 (Fed. Cir. 2013)). 

II

Ferring first argues that “[t]he district court’s application of equitable estoppel to Ferring’s claims for correction 

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of inventorship under 35 U.S.C. § 256 prior to the issuance 

of any patents is contrary to the plain language of the statute and this [c]ourt’s precedent.” Appellants’ Br. 28.

Stated more clearly, Ferring claims that, because its written exchanges with Fein predated the issuance of the Fein

patents, those exchanges should not have been factored 

into the court’s equitable estoppel analysis, leaving nothing 

else upon which to predicate the judgment on Ferring’s 

claims. During oral argument, however, Ferring conceded 

that our decision in MCV, Inc. v. King-Seeley Thermos Co., 

870 F.2d 1568, 1572 (Fed. Cir. 1989), stands for the proposition that a court may consider pre-issuance conduct in assessing the application of equitable estoppel to § 256 

claims, and that MCV remains good law. Oral Arg. at 1:48–

3:02, http://oralarguments.cafc.uscourts.gov/default.aspx?

fl=20-1098_09032020.mp3. 

MCV applied a formulation of equitable estoppel that 

included an element of “unreasonable and inexcusable delay in filing suit.” 870 F.2d at 1571. This court subsequently overruled that aspect of the formulation in A.C. 

Aukerman Co. v. R.L. Chaides Constr. Co., 960 F.2d 1020, 

1042 (Fed. Cir. 1992) (en banc), abrogated on other grounds 

by SCA Hygiene Prods. Aktiebolag v. First Quality Baby 

Prods., LLC, 137 S. Ct. 954, 959 (2017). See Aukerman, 

960 F.2d at 1042 (“The test set out in Jamesbury [Corp. 

v. Litton Industrial Products, Inc., 839 F.2d 1544 (Fed. Cir.

1988))] confusingly intertwines the elements of laches and 

equitable estoppel and is expressly overruled. Delay in filing suit may be evidence which influences the assessment 

of whether the patentee’s conduct is misleading but it is not 

a requirement of equitable estoppel.”). All other aspects of 

the analysis in MCV, however, were left intact.

In MCV, we applied to a correction of inventorship 

claim the rule from “infringement situations” that “an assertion of right followed by silence on the part of the patentee may give rise to an estoppel if the patentee’s silence 

is sufficiently misleading.” 870 F.2d at 1572. The putative 

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co-inventor (and founder of MCV) “conferred with [patentee Halsey Taylor’s representative] on drafts of the 

claims” and suggested that he be included as a co-inventor 

on Halsey Taylor’s application. Id. at 1569. When Halsey 

Taylor “responded that company policy prohibited the 

naming of non-employees on company patents,” MCV’s 

founder replied that “the exclusive right to market the water coolers was more valuable to MCV than patent rights, 

and that he would ‘help[] in any way [h]e could to facilitate 

the submission of the . . . patent.’” Id. (alterations in original). When things later soured between the parties with 

respect to their marketing agreement, MCV brought a correction of inventorship claim. Id. We affirmed the district 

court’s grant of summary judgment that MCV was equitably estopped from asserting a correction of inventorship 

claim, noting that “MCV not only remained silent about coinventorship after [its founder’s] 1982 discussion with 

[Halsey Taylor], but affirmatively represented to Halsey 

Taylor that it would assist ‘in any way [it] could’ to obtain 

the patent.” Id. at 1572 (third alteration in original). Because MCV’s founder “knew Halsey Taylor was seeking a 

patent, and knew what was being claimed,” we reasoned 

that “it was incumbent upon him timely, explicitly and tenaciously to apprise Halsey Taylor of his purported inventorship so it could be maturely considered.” Id. at 1573.

Retreating from the per se rule it initially advanced, 

Ferring then suggested that Radio Systems and John Bean 

support a rule that “when the scope of the issued patents

[is] different than what was before the parties that led to 

the alleged misleading conduct or inaction then the defense 

of equitable estoppel cannot apply.” Oral Arg. at 2:47–3:45; 

see Radio Sys., 709 F.3d 1124; John Bean, 887 F.3d 1322.

Radio Systems does not stand for Ferring’s revised

rule, however. The two patents at issue in Radio Systems

differed in claim scope, but only the first-issued patent was 

mentioned in a 2005 demand letter accusing Radio Systems’s predecessor of infringement. 709 F.3d at 1126, 

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18 FERRING B.V. v. ALLERGAN, INC.

1131. Radio Systems’s predecessor responded that the 

first-issued patent was invalid. Id. at 1126. The second 

patent issued about two and a half years after the 2005 demand letter. Id. There was no further communication between the parties until 2009, when Radio Systems received 

a second demand letter accusing Radio Systems of infringing both patents. Id. In 2010, Radio Systems filed an action seeking declaratory judgment of noninfringement and 

invalidity of both patents and the patent owner counterclaimed for infringement of both patents. Id. at 1126–27. 

The district court held that equitable estoppel barred the 

patent owner’s infringement claims as to both patents 

based on the 2005 demand letter and subsequent silence. 

Id. at 1130. We affirmed the district court’s holding as to 

the first patent, concluding that Radio Systems and its predecessor were in privity and equitable estoppel applied to 

Radio Systems as a successor-in-interest. Id. at 1131. We 

then reversed the district court’s holding that equitable estoppel applied to bar the patent owner’s infringement 

claims as to the second patent. Id. Because “[t]he first notice of infringement to Radio Systems regarding the [second] patent” occurred in the 2009 demand letter, there was 

“simply no misleading conduct or silence by [the patent 

owner] to indicate that it did not intend to enforce the [second] patent against Radio Systems.” Id. Differences in 

claim scope did not alone dictate the second of our conclusions. It was the absence of any communication regarding 

what became the claims in the second patent that was most 

critical to our holding.

Nor does John Bean stand for a broad rule that equitable estoppel does not apply whenever there is a difference 

in scope between the issues implicated in discussions giving rise to potentially misleading conduct and the patent 

claims at issue in subsequent litigation. In John Bean, the 

reexamined claims that formed the basis of John Bean’s infringement suit were “heavily amended” or added following 

an ex parte reexamination twelve years after the 

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FERRING B.V. v. ALLERGAN, INC. 19

defendant’s original demand letter (to which John Bean 

never responded) challenging the validity of the asserted 

patent. 887 F.3d at 1324–26. John Bean did not allege any 

infringing activity occurring prior to the issuance of the 

reexamination certificate. Id. at 1326. We concluded that 

“[t]he district court abused its discretion by applying equitable estoppel to bar John Bean’s infringement action without considering how the ex parte reexamination affected 

the [asserted] patent claims.” Id. at 1329. Under the circumstances presented, we reasoned that John Bean narrowed its claims during reexamination to such an extent 

that the defendant’s invalidity analysis communicated in 

the demand letter would not apply to John Bean’s reissued 

claims. See id. at 1328. We did not announce a blanket 

rule that any change to claim scope between the time of 

communications giving rise to allegedly misleading conduct and the filing of a patent suit would preclude the application of equitable estoppel.

As “equitable estoppel is not limited to a particular factual situation nor subject to resolution by simple or hard 

and fast rules,” Aukerman, 960 F.2d at 1041, we decline to 

adopt a bright-line rule that equitable estoppel cannot apply whenever the scope of the issued patent is different 

than what the parties discussed in communications leading

to the allegedly misleading conduct. Thus, while differences in claim scope are relevant to the equitable estoppel 

inquiry, their mere existence does not render pre-issuance 

conduct or communications irrelevant.

While we reject Ferring’s bright-line rule with respect 

to the relevance of pre-issuance communications, that does 

not mean material differences in the potential patent 

claims discussed pre-issuance and the claims that ultimately issue need not be considered. And it, importantly, 

does not mean that such differences may not give rise to 

material issues of fact regarding the implications of any period of silence following pre-issuance communications. We 

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20 FERRING B.V. v. ALLERGAN, INC.

turn to that question in the context of Ferring’s second argument.

III

Ferring also asserts that, in granting Defendants’ motion for summary judgment, the district court improperly 

resolved issues of fact in favor of Defendants. Ferring principally argues that the district court erred in concluding 

that Ferring engaged in misleading conduct because that 

was not the only possible inference from the evidence. On 

this point, we agree with Ferring. 

A

In the “most common situation” giving rise to equitable 

estoppel, “the patentee specifically objects to the activities 

currently asserted as infringement in the suit and then 

does not follow up for years.” Id. at 1042. Equitable estoppel has three elements:

(1) the patentee engages in misleading conduct 

that leads the accused infringer to reasonably infer 

that the patentee does not intend to assert its patent against the accused infringer; (2) the accused 

infringer relies on that conduct; and (3) as a result 

of that reliance, the accused infringer would be materially prejudiced if the patentee is allowed to proceed with its infringement action. 

John Bean, 887 F.3d at 1327 (citing Scholle, 133 F.3d 

at 1471); see also Aukerman, 960 F.2d at 1041 (quoting 

D.B. Dobbs, Handbook on the Law of Remedies § 2.3, at 42 

(1973)). “To justify summary judgment of equitable estoppel, any inference that a patentee made a misleading communication by omission or acquiescence ‘must be the only

possible inference from the evidence.’” SCA Hygiene Prods. 

Aktiebolag v. First Quality Baby Prods., LLC, 767 F.3d 

1339, 1350 (Fed. Cir. 2014) (quoting Aukerman, 960 F.2d 

at 1044), vacated in part on other grounds, 137 S. Ct. 

at 967.

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B

We agree with Ferring that the Speranza correspondence is subject to interpretation and does not support the 

single inference that Ferring, by its statements in the letters and subsequent silence, acquiesced in Fein’s sole inventorship of the material in the Fein patents, particularly 

because the claims in those patents are not limited to, and 

do not even mention, the sublingual route of delivery of 

desmopressin. We conclude that the district court erred 

when it concluded as a matter of law that “Ferring’s present application to correct inventorship contradicts its earlier position in the Speranza correspondence,” Ferring, 

253 F. Supp. 3d at 718, and, accordingly, abused its discretion in granting summary judgment of equitable estoppel. 

1

The district court’s decision rested on the erroneous 

view that the scope of the Speranza correspondence and the 

scope of Fein’s application claims were commensurate with 

the scope of Fein’s issued claims. The district court abused 

its discretion by applying equitable estoppel to bar Ferring’s § 256 claims because it failed to address material differences in the scope of Fein’s issued patent claims as 

compared to the invention described in the Speranza correspondence and Fein’s application claims. See John Bean, 

887 F.3d at 1329.

To be sure, the parties understood from the Speranza 

correspondence that Ferring disavowed any ownership 

claim to the sublingual, transmucosal route of delivery of 

desmopressin and its associated low-dosage possibilities

that Fein identified as his invention in the Speranza correspondence. When Fein advised Ferring that he intended

independently to pursue patent protection for “the sub-lingual administration route and the associated low dosage 

possibilities enabled by same,” J.A. 539, Ferring responded 

that it “will not be pursuing this claim” because “[t]he low 

dosage possibilities enabled by the sublingual 

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22 FERRING B.V. v. ALLERGAN, INC.

administration route are already available in the public domain,” J.A. 542. 

But, contrary to those representations to Ferring, Fein 

did not pursue patent protection for claims limited to sublingual (or transmucosal) administration of desmopressin. 

Instead, Fein pursued claims untethered to sublingual administration of desmopressin. E.g., J.A. 587–89. In fact, 

most of Fein’s PCT application claims are untethered to 

any route of administration. Most of Fein’s PCT application claims cover pharmaceutical compositions comprising

various low doses of desmopressin, some of which are further limited to require that the claimed pharmaceutical 

composition is effective to establish various desmopressin 

plasma/serum concentrations. Indeed, none of Fein’s PCT 

or ’100 application claims and none of his issued claims are

limited to sublingual administration of desmopressin. See

’203 patent at col. 28, ll. 7–56; ’321 patent at col. 28, l. 34–

col. 30, l. 18; ’761 patent at col. 28, l. 39–col. 30, l. 19; 

J.A. 587–89, 651. Very few of Fein’s PCT or ’100 application claims and very few of his issued claims are limited to 

a transmucosal route of administration. See id. Fein’s PCT 

and ’100 application claims are a sweeping departure from 

his sublingual low-dose desmopressin invention as he described it to Ferring. Importantly, Fein sought patent protection for his claims despite Ferring’s prior warning to 

him that Ferring could not “say now that Ferring will not 

make any claim as to ownership of any other material Dr[.]

Fein may include in any patent application . . . without seeing the text.” J.A. 542. In view of Ferring’s representation 

to Fein that it could not disclaim ownership of any material 

beyond the sublingual administration route and associated 

low-dose possibilities, a reasonable factfinder could conclude that it would have been unreasonable for Fein to infer from Ferring’s pre-2004 communications that Ferring 

intended to relinquish inventorship rights in the issued 

claims of the Fein patents.

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Serenity argues that Ferring did acquiesce in Fein’s inventorship of patent claims untethered to the sublingual 

route of administration when it remained silent after 

learning, in December 2004, “of exactly what [Fein] was 

claiming—through the claims in his published PCT Application and ’100 Application.”4 Appellees’ Br. 32. The district court agreed with Serenity, resting its decision that 

Ferring engaged in misleading conduct in part on its determination that “[t]he low-dosage invention as described in 

the PCT at issue in the Speranza correspondence is the 

same subject matter detailed in the patents-in-suit, down 

to the specific numerical quantity of desmopressin to be 

used.” Ferring, 253 F. Supp. 3d at 718. The district court 

implicitly concluded that Ferring had notice of the invention in Fein’s issued claims as of Ferring’s December 2004 

letter, by virtue of that letter’s reference to Fein’s 2003 PCT 

application. 

4 Though Speranza’s second December 14, 2004 letter states that Speranza included a copy of the ’100 application with the letter, J.A. 550, Ferring argues that no copy 

was ever provided, Reply 24. Regardless, our assessment 

of Fein’s PCT application applies equally to the ’100 application, because like Fein’s PCT application, the ’100 application does not recite any claims with a duration of action 

limitation. See J.A. 651. 

There is no evidence that Ferring had notice of Fein’s 

’615 application (filed in 2007) or his ’074 application (filed 

in 2008), which matured into Fein’s method of treatment 

patents. Indeed, the Speranza correspondence does not indicate that Fein was pursuing any additional patents beyond those he expressly identified by application number. 

On this record, a reasonable factfinder could conclude that 

Ferring had no obligation or incentive to monitor patent 

filings to identify any additional patent applications Fein 

had chosen to prosecute.

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24 FERRING B.V. v. ALLERGAN, INC.

But that conclusion rested on an inadequate claim 

scope analysis, particularly as to Fein’s issued claims containing duration of action limitations. In discussing the 

relative scope of Fein’s issued claims and the application 

claims, the district court did not point to any claims. Instead, the district court stated only that “[t]he low-dosage 

invention as described in the PCT at issue in the Speranza 

correspondence is the same subject matter detailed in the 

patents-in-suit, down to the specific numerical quantity of 

desmopressin to be used.” Id. The district court’s conclusion that the claim scope of Fein’s issued claims is the same 

as that of his application claims fails to account for the fact 

that most of Fein’s issued claims contain duration of action 

limitations completely absent from Fein’s application 

claims. Compare, e.g., ’203 patent at col. 28, ll. 7–56, with 

J.A. 587–89. Ferring based its § 256 claims in part on the 

very duration of action limitations the district court overlooked. See, e.g., Complaint at 26–33, Ferring B.V. v. Allergan, Inc., No. 12-cv-2650 (S.D.N.Y. Apr. 5, 2012), ECF 

No. 1; J.A. 1155 (“Indeed, the ’203, ’321, and ’761 patents 

claim the very . . . duration of action (around 4–6 hours) 

that Dr. Norgaard and Dr. Senderovitz developed before 

any of Fein’s alleged conversations with Nardi.”). 

In the absence of notice to Ferring of Fein’s claim to 

inventorship of the duration of action limitations, a reasonable factfinder could find that Ferring did not mislead Fein 

regarding Ferring’s claims of inventorship with respect to 

any of Fein’s application claims or issued claims reciting a 

duration of action limitation.

2

Setting aside the differences in scope between Fein’s 

application claims and his issued claims, and the parties’ 

dispute as to whether Ferring ever received or reviewed a 

copy of the ’100 application, we must vacate the district 

court’s summary judgment of equitable estoppel because 

the district court’s interpretation of the Speranza 

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correspondence is not the only reasonable one. See SCA

Hygiene, 767 F.3d at 1350 (“To justify summary judgment

of equitable estoppel, any inference that a patentee made a 

misleading communication by omission or acquiescence 

‘must be the only possible inference from the evidence.’”

(quoting Aukerman, 960 F.2d at 1044)).

In December 2004, Ferring wrote to Fein expressing 

surprise that Fein had proceeded with his PCT “application 

containing an invention to which [Ferring] believe[s] he 

has no entitlement and which in particular discloses information confidential and proprietary to Ferring to which 

Dr[.] Fein had confidential access during his agreement as 

[a] consultant.” J.A. 544. Ferring’s letter provided an example, noting that Ferring’s confidential results from its 

CS004 study “appear virtually verbatim” on page 30 of 

Fein’s PCT application. Id. Ferring further informed Fein 

that “Ferring will take all necessary steps to protect its 

rights and interests,” and stated that Ferring would “commence formal action” if it “d[id] not receive a full and satisfactory explanation within 14 days.” Id.

Serenity argues that Ferring’s December 2004 letter 

stated concerns regarding both Fein’s use of Ferring’s confidential information and Fein’s lack of inventorship interest (i.e., lack of “entitlement”) in the invention in his 

published PCT application. Though Serenity’s position is 

not unreasonable, Ferring’s December 2004 letter could 

also reasonably refer only to Ferring’s concerns regarding 

Fein’s use of Ferring’s confidential information. A reasonable factfinder could interpret Ferring’s use of the phrase 

“and which in particular” to explain further the basis for

Ferring’s assertion that Fein had “no entitlement” to the 

invention in his PCT application, rather than to state

Fein’s misuse of confidential information as a separate concern from lack of “entitlement.”

Speranza’s December 2004 responses confirm that Fein 

contemporaneously understood Ferring’s “no entitlement” 

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26 FERRING B.V. v. ALLERGAN, INC.

assertion to lend itself to multiple reasonable interpretations. Indeed, Speranza’s first responsive letter “confess[ed] to not entirely understanding” Ferring’s “no 

entitlement” assertion and set forth three alternative interpretations. J.A. 546. First, and “as would appear” from 

Ferring’s December 2004 letter, Ferring’s “‘no entitlement’ 

statement relates to the assertion that the application ‘discloses information confidential and proprietary to Ferring.’” Id. Second, Ferring’s “no entitlement” assertion 

could “refer[] to the belief of Ferring that this low dosage 

invention of Dr. Fein simply is not patentable because of 

prior art, as was expressed in [Ferring’s] letter of 29 April 

2003.” Id. Third, Ferring’s “no entitlement” assertion 

could be “somehow intended to suggest that Dr. Fein is not 

the inventor of the claimed low dose invention and/or that 

Dr. Fein cannot assert ownership rights to it.” Id.

Elaborating on the third possibility, Speranza mischaracterized Ferring’s April 29, 2003 letter as “confirm[ing] 

that Ferring would not be pursuing any claim with respect 

to low dose desmopressin.” J.A. 547. In fact, in that letter, 

Ferring explained only that it would not pursue claims directed to “[t]he low dosage possibilities enabled by the sublingual administration route.” J.A. 542 (emphasis added). 

To the extent Speranza’s articulation of the third possibility gave rise to a duty for Ferring to respond, a reasonable 

factfinder could find that Speranza’s blatant mischaracterization of the scope of Ferring’s prior disclaimer relieved 

Ferring of any such duty.

In finding that Ferring’s December 2004 threat of “immediate legal action” and subsequent silence misled Fein 

into thinking that Ferring had relinquished any inventorship rights in the inventions claimed in Fein’s PCT and 

’100 applications, the district court cast aside Speranza’s 

first two interpretations of Ferring’s “no entitlement” assertion in favor of the third. See Ferring, 253 F. Supp. 3d 

at 718. As the third possibility bears the closest relation to 

the inventorship dispute underlying Ferring’s subsequent 

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§ 256 claims, the district court’s decision to credit the third 

possibility over the first two drew an inference against Ferring. This was improper at summary judgment, particularly when the evidence shows that Fein believed the first 

possibility to be the most likely.5 See Kuebel, 643 F.3d 

at 358 (explaining that at summary judgment, courts are 

to “constru[e] the evidence in the light most favorable to 

the nonmoving party”). In view of the varying reasonable 

interpretations of the Speranza correspondence, we must 

vacate the district court’s summary judgment of equitable 

estoppel and remand for further proceedings. See SCA Hygiene, 767 F.3d at 1350.

IV

Finally, Ferring asserts that the district court erred in 

deciding that Ferring was equitably estopped from asserting its § 256 claims because the court failed to consider 

“other evidence and facts respecting the equities of the parties.” Appellants’ Br. 49 (quoting Aukerman, 960 F.2d 

at 1043). Specifically, Ferring maintains that in assessing 

Defendants’ unclean hands, the district court erred by ignoring evidence that Fein intentionally and deliberately 

copied Ferring’s CS009 clinical study protocol for use in his 

own clinical studies. While we have already concluded that 

a remand is appropriate for other reasons, we address this 

issue because it will remain live on remand. 

“[T]he trial court must, even where the three elements 

of equitable estoppel are established, take into consideration any other evidence and facts respecting the equities of 

the parties in exercising its discretion and deciding 

whether to allow the defense of equitable estoppel to bar 

the suit.” Aukerman, 690 F.2d at 1043. Indeed, “equitable 

5 Having concluded that the district court erred in its 

misleading conduct analysis, we do not address the parties’ 

arguments regarding reliance and prejudice.

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28 FERRING B.V. v. ALLERGAN, INC.

estoppel is not limited to a particular factual situation nor 

subject to resolution by simple or hard and fast rules.” Id.

at 1041.

Ferring’s opposition to Defendants’ motion for summary judgment of equitable estoppel raised four bases to 

support the argument that Defendants’ unclean hands 

should preclude the district court from granting equitable 

relief. Ferring asserted: (1) Defendants misrepresented 

that Allergan had viewed the Speranza correspondence 

when conducting its diligence review prior to investing in 

Serenity and Reprise; (2) Defendants hired a third party to 

recover confidential Ferring documents from Nardi’s computer, which documents Ferring had previously deleted 

pursuant to Nardi’s employment agreement; (3) Defendants’ counsel organized meetings between defense witnesses to coordinate their testimony, after which Fein 

submitted a supplemental witness statement modifying his 

testimony; and (4) Fein duplicated Ferring’s CS009 clinical 

study protocol in his own CNF Desmo PK200301 clinical 

study, misrepresented it as his own, and subsequently included data from the study in the Fein patents as Example 8. J.A. 1169–71. With respect to Fein’s copying, 

Ferring further argued that Fein had misrepresented to 

the USPTO in his patent applications that he had evaluated pharmacokinetic parameters at each desmopressin 

dose level. J.A. 1170, 1205–06. Ferring cited evidence that 

Fein did not attempt to measure plasma/serum levels of 

desmopressin in the CNF Desmo PK200301 study before 

he filed his patent applications, because the plasma samples from the study were still in frozen storage as of November 2006. Id. (citing S.A. 4234).

Despite the district court’s statement that it “has also 

considered and rejects Ferring’s unclean hands arguments,” the court discussed only Ferring’s first three arguments. Ferring, 253 F. Supp. 3d at 721. The district court’s 

opinion does not mention Ferring’s CS009 study or Example 8 of the Fein patents at all. This leaves us no basis to 

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infer that the district court considered Ferring’s evidence

that Fein copied Ferring’s CS009 study and made related 

misrepresentations to the USPTO. We therefore conclude 

that the district court abused its discretion in granting 

summary judgment of equitable estoppel because the court 

failed to consider all relevant evidence regarding the equities of the parties. See Aukerman, 690 F.2d at 1043; Rothschild Connected Devices Innovations, LLC v. Guardian 

Protection Servs., Inc., 858 F.3d 1383, 1388 (Fed. Cir. 2017) 

(“A district court abuses its discretion when, as here, it 

‘fail[s] to conduct an adequate inquiry.’” (alteration in original) (quoting Atl. Research Mktg. Sys., Inc. v. Troy, 

659 F.3d 1345, 1360 (Fed. Cir. 2011))).

CONCLUSION

We have considered the parties’ remaining arguments 

and do not find them persuasive. For the foregoing reasons, we vacate the district court’s judgment and remand 

for further proceedings consistent with this opinion.

VACATED AND REMANDED

COSTS

The parties shall bear their own costs.

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