United States Court of Appeals 

for the Federal Circuit ______________________ 

ASTELLAS PHARMA, INC., ASTELLAS IRELAND 

CO., LTD., ASTELLAS PHARMA GLOBAL 

DEVELOPMENT, INC.,

Plaintiffs-Appellants

v.

SANDOZ INC., ZYDUS PHARMACEUTICALS (USA) 

INC., ZYDUS LIFESCIENCES LTD., DBA ZYDUS 

CADILA, LUPIN LTD., LUPIN 

PHARMACEUTICALS, INC., LEK 

PHARMACEUTICALS, D.D.,

Defendants-Appellees

AUROBINDO PHARMA LTD., AUROBINDO 

PHARMA USA, INC., AUROLIFE PHARMA LLC, 

ACTAVIS ELIZABETH LLC, PRINSTON 

PHARMACEUTICAL INC., ZHEJIANG HUAHAI 

PHARMACEUTICAL CO., LTD., HUAHAI US INC., 

SOLCO HEALTHCARE U.S., LLC, WINDLAS 

HEALTHCARE PVT. LTD., WINDLAS BIOTECH

LTD., TEVA PHARMACEUTICALS USA, INC.,

Defendants

______________________ 

2023-2032, 2023-2063, 2023-2089

______________________ 

Appeals from the United States District Court for the 

District of Delaware in Nos. 1:20-cv-01589-JFB-CJB, 1:21-

cv-00425-JFB-CJB, 1:21-cv-00664-JFB-CJB, Senior Judge 

Joseph F. Bataillon.

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2 ASTELLAS PHARMA, INC. v. SANDOZ INC. 

______________________ 

Decided: September 18, 2024

______________________ 

PAUL WHITFIELD HUGHES, III, McDermott Will & Emery LLP, Washington, DC, argued for plaintiffs-appellants. 

Also represented by ANDREW LYONS-BERG, CHARLES H.

SEIDELL; JASON ALBERT LEONARD, SIMON ROBERTS, New 

York, NY; DANIEL M. SILVER, McCarter & English, LLP, 

Wilmington, DE. 

 WILLIAM R. ZIMMERMAN, Knobbe, Martens, Olson & 

Bear, LLP, Washington, DC, argued for all defendants-appellees. Defendants-appellees Lupin Ltd., Lupin Pharmaceuticals, Inc. also represented by ANDREA L. CHEEK; 

CAROL PITZEL CRUZ, Seattle, WA.

 KEVIN PATRICK BURKE, Rakoczy Molino Mazzochi 

Siwik LLP, Chicago, IL, for defendants-appellees Sandoz 

Inc., Lek Pharmaceuticals, d.d. Also represented by 

DEANNE M. MAZZOCHI, WILLIAM A. RAKOCZY, RACHEL 

PERNIC WALDRON. 

 MICHAEL GAERTNER, Locke Lord LLP, Chicago, IL, for 

defendants-appellees Zydus Pharmaceuticals (USA) Inc., 

Zydus Lifesciences Ltd. Also represented by DAVID BRIAN 

ABRAMOWITZ, HUGH S. BALSAM, CAROLYN ANNE BLESSING,

EMILY SAVAS, JONATHAN B. TURPIN. 

______________________ 

Before LOURIE, PROST, and REYNA, Circuit Judges.

LOURIE, Circuit Judge.

Astellas Pharma, Inc., Astellas Ireland Co., Ltd., and 

Astellas Pharma Global Development, Inc. (collectively, 

“Astellas”) appeal from the final judgment of the United 

States District Court for the District of Delaware. 

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ASTELLAS PHARMA, INC. v. SANDOZ INC. 3

Following a five-day bench trial on issues of infringement 

and validity under 35 U.S.C. § 112, the district court determined, sua sponte, that claims 5, 20, and 25 of U.S. Patent 

10,842,780 (“the ’780 patent”) are invalid under 35 U.S.C. 

§ 101 as directed to an ineligible natural law. Astellas 

Pharma Inc. v. Sandoz Inc., No. 20-cv-1589, 2023 WL 

3934386 (D. Del. June 9, 2023) (“Decision”). For the reasons set forth below, we vacate the judgment and remand.

BACKGROUND

I 

In 2012, the U.S. Food and Drug Administration 

(“FDA”) approved the New Drug Application (“NDA”) for 

extended-release mirabegron tablets for the treatment of 

overactive bladder (“OAB”), which Astellas markets and 

sells under the brand name Myrbetriq®. Mirabegron is a 

beta-3 agonist that stimulates beta receptors in the bladder, thereby inducing bladder relaxation and improving 

bladder function.

During the development of Myrbetriq, Astellas discovered that immediate-release formulations of mirabegron 

exhibit an undesirable “food effect,” meaning that the bioavailability of the drug is affected by the presence or absence of food in a patient’s stomach. Astellas observed that 

when patients took the drug with a meal, the levels of mirabegron that were absorbed into the blood were too low to 

impart any therapeutic benefit. But when patients took 

the drug on an empty stomach, mirabegron was absorbed 

too rapidly, reaching potentially toxic concentrations in the 

blood. To solve this problem, Astellas developed sustainedrelease formulations of mirabegron, which abated the undesirable food effect. Those formulations are covered by 

the claims of the ’780 patent.

The ’780 patent contains two independent claims, each 

of which is directed to a sustained-release pharmaceutical 

composition comprising mirabegron. Independent claim 1, 

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4 ASTELLAS PHARMA, INC. v. SANDOZ INC. 

from which asserted claims 5 and 20 ultimately depend, recites:

1. A pharmaceutical composition, comprising 10 

mg to 200 mg of [mirabegron], or a pharmaceutically acceptable salt thereof, in a sustained release 

hydrogel-forming formulation comprising a hydrogel-forming polymer having an average molecular 

weight of 100,000 to 8,000,000 and an additive having a water solubility of at least 0.1 g/mL at 20±5° 

C.,

wherein the hydrogel-forming polymer is at least 

one compound selected from the group consisting of 

polyethylene oxide, hydroxypropyl methylcellulose, 

hydroxypropyl cellulose, carboxymethyl cellulose 

sodium, hydroxyethyl cellulose, and a carboxyvinyl 

polymer,

wherein the additive is at least one selected from 

the group consisting of polyethylene glycol, polyvinylpyrrolidone, D-mannitol, D-sorbitol, xylitol, lactose, sucrose, anhydrous maltose, D-fructose, 

dextran, glucose, polyoxyethylene hydrogenated 

castor oil, polyoxyethylene polyoxypropylene glycol, polyoxyethylene sorbitan higher fatty acid ester, sodium chloride, magnesium chloride, citric 

acid, tartaric acid, glycine, β-alanine, lysine hydrochloride, and meglumine, and

wherein a drug dissolution rate from the pharmaceutical composition is 39% or less after 1.5 hours, 

and at least 75% after 7 hours, as measured in accordance with United States Pharmacopoeia in 900 

mL of a USP buffer having a pH of 6.8 at a paddle 

rotation speed of 200 rpm.

’780 patent at col. 20, ll. 19–47; J.A. 8617–18 (Certificate of 

Correction). Asserted claim 5, which depends directly from 

claim 1, recites:

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ASTELLAS PHARMA, INC. v. SANDOZ INC. 5

5. The pharmaceutical composition according to 

claim 1, wherein the hydrogel-forming polymer is 

at least one compound selected from the group consisting of polyethylene oxide, hyd[r]oxypropyl 

methylcellulose, and hydroxypropyl cellulose. 

’780 patent at col. 20, ll. 61–65; J.A. 8617–18 (Certificate of 

Correction). Asserted claim 20, which depends from claim 

1 by way of claims 16 and 18, recites:

20. A method for treating overactive bladder comprising administering the tablet according to claim 

18 to a subject in need thereof.

’780 patent at col. 22, ll. 6–8. Claim 18 recites “[a] tablet, 

comprising the pharmaceutical composition according to 

claim 16,” id. at col. 22, ll. 1–2, and claim 16 recites “[t]he 

pharmaceutical composition according to claim 1, comprising 10 mg to 200 mg of [mirabegron],” id. at col. 21, ll. 

30–33.

Independent claim 22, from which asserted claim 25 ultimately depends, recites:

22. A pharmaceutical composition, comprising 10 

mg to 200 mg of [mirabegron], or a pharmaceutically acceptable salt thereof, in a sustained release 

hydrogel-forming formulation comprising a means 

for forming a hydrogel and a means for ensuring 

penetration of water into the pharmaceutical composition, 

wherein a drug dissolution rate from the pharmaceutical composition is 39% or less after 1.5 hours, 

and at least 75% after 7 hours, as measured in accordance with United States Pharmacopoeia in 900 

mL of a USP buffer having a pH of 6.8 at a paddle 

rotation speed of 200 rpm.

Id. at col. 22, ll. 13–25. Asserted claim 25, which depends 

from independent claim 22 by way of claim 23, recites:

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6 ASTELLAS PHARMA, INC. v. SANDOZ INC. 

25. A tablet, comprising the pharmaceutical composition according to claim 23.

Id. at col. 22, ll. 32–33. Claim 23 recites “[t]he pharmaceutical composition according to claim 22, comprising 10 mg 

to 200 mg of [mirabegron].” Id. at col. 22, ll. 26–29.

In short, asserted claims 5, 20, and 25 are generally directed to a pharmaceutical composition comprising mirabegron, a method of treating OAB using that composition, 

and a tablet comprising that composition, respectively.

II

On November 24, 2020, the day that the ’780 patent 

issued, Astellas sued each of Sandoz Inc., Zydus Pharmaceuticals (USA) Inc., Zydus Lifesciences Ltd., dba Zydus 

Ca-Dila, Lupin Ltd., Lupin Pharmaceuticals, Inc., and Lek 

Pharmaceuticals, D.D. (collectively, “Sandoz”) for patent 

infringement under 35 U.S.C. § 271(e)(2)(A) based on the 

Abbreviated New Drug Application (“ANDA”) each had 

submitted in 2016, seeking FDA approval to market and 

sell generic versions of Myrbetriq.1 The cases were consolidated and proceeded to discovery.

On July 7, 2021, Sandoz produced its initial invalidity 

contentions. See J.A. 651–52. In those contentions, Sandoz 

claimed that the asserted claims were invalid under each 

of 35 U.S.C. §§ 102 (for anticipation), 103 (for obviousness), 

and 112 (for each of written description, enablement, and 

indefiniteness). Astellas Br. 11–12. Over a year later, on 

August 29, 2022, Sandoz produced its final invalidity contentions, maintaining each of those same grounds of 

1 Astellas previously sued Sandoz in 2016 for infringement of certain then-listed Orange Book patents. 

E.g., Astellas Pharma Inc. v. Sandoz Inc., No. 16-cv-952 (D. 

Del. filed Oct. 14, 2016). But the parties thereafter reached 

a settlement, and those cases were dismissed.

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ASTELLAS PHARMA, INC. v. SANDOZ INC. 7

invalidity. Id. at 12; J.A. 1501–02. Sandoz did not pursue 

an invalidity defense under 35 U.S.C. § 101 during the discovery phase of the litigation. 

Nearing the February 6, 2023 trial date, the parties 

continued to narrow their theories of the case. In mid-January, the parties filed a joint proposed pre-trial order, in 

which Sandoz agreed to limit its invalidity defenses to obviousness under 35 U.S.C. § 103 and each of written description, enablement, and indefiniteness under § 112. See 

generally J.A. 6505–36 (Sandoz’s Statement of Issues of 

Law that Remain to be Litigated). Then, on February 1, 

2023, the parties filed a joint stipulation in which Astellas 

agreed to assert only claims 5, 20, and 25 of the ’780 patent, 

while Sandoz agreed to limit its invalidity defenses to only 

those arising under § 112. J.A. 6591–93. Accordingly, in 

the days leading up to trial, Sandoz waived any challenge 

to the asserted claims arising under §§ 102 and 103. The 

five-day bench trial came and went with no discussion, let 

alone argument, from the parties as to the patent eligibility 

of the asserted claims. Nor did that issue arise in the parties’ post-trial briefing.

Nevertheless, the district court issued a final decision 

holding asserted claims 5, 20, and 25 of the ’780 patent invalid as directed to patent-ineligible subject matter under 

35 U.S.C. § 101. Decision at *2. Relying on Astellas’s statement in its post-trial briefing, that, in the context of enablement under § 112, the “inventive concept of the ’780 

Patent was discovering the dissolution rate that would address the food effect and achieving it using previously 

known formulation technology,” id. (quoting Astellas’s 

post-trial rebuttal brief, J.A. 7416) (emphases omitted), the 

district court determined that “Astellas concedes that the 

’780 patent is enabled because it claims invalid subject 

matter: a natural law applied via routine, conventional, 

and well-known methods.” Id. (citing Mayo Collaborative 

Servs. v. Prometheus Lab’ys, Inc., 566 U.S. 66 (2012)). 

Thus, because the claimed invention “reflects merely the 

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8 ASTELLAS PHARMA, INC. v. SANDOZ INC. 

discovery of the food-effect-resolving dissolution profile,” 

the district court deemed the asserted claims invalid as patent ineligible. Id. at *1.

Following the entry of judgment, Sandoz, the prevailing party, moved pursuant to Federal Rule of Civil Procedure 52(b) for the district court to make additional findings 

of fact and conclusions of law on the issues actually presented at trial—namely, infringement and validity under 

§ 112. J.A. 8507–11. In that motion, Sandoz argued that 

it anticipated that Astellas would appeal the judgment and 

argue that “a § 101 defense [] was not presented at trial or 

in the post-trial briefing” and that the defense “is currently 

not set forth in the [c]ourt’s opinion in terms of the claim 

language itself.” Id. at 8508–09 (citing Synopsys, Inc. v. 

Mentor Graphics Corp., 839 F.3d 1138, 1149 (Fed. Cir. 

2016), for the proposition that a § 101 inquiry must be 

based on the language of the claims themselves). The district court denied that motion, concluding that, despite 

Sandoz’s concerns, “[t]he [c]ourt could not have better invoked [Mayo].” Astellas Pharma Inc. v. Sandoz Inc., No. 

20-cv-1589 (D. Del. June 27, 2023), ECF 577, J.A. 8512–14 

(“Rule 52(b) Decision”).

Astellas timely appealed. We have jurisdiction under 

28 U.S.C. § 1295(a)(1).

DISCUSSION

I 

The Supreme Court has made clear that, “[i]n our adversary system, in both civil and criminal cases, in the first 

instance and on appeal, we follow the principle of party 

presentation. That is, we rely on the parties to frame the 

issues for decision and assign to courts the role of neutral 

arbiter of matters the parties present.” Greenlaw v. United 

States, 554 U.S. 237, 243 (2008). By rendering its decision 

on a ground not raised by any party at any stage of the proceedings, and by expressly declaring that it “sits not [as] an 

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ASTELLAS PHARMA, INC. v. SANDOZ INC. 9

arbiter to resolve the disputes on the parties’ favored terrain,” Decision at *2, the district court disregarded the 

longstanding principle of party presentation and, in doing 

so, abused its discretion. United States v. Sineneng-Smith, 

590 U.S. 371, 375 (2020) (providing that departures from 

the principle of party presentation are reviewed for abuse 

of discretion); United States v. Dowdell, 70 F.4th 134, 146 

(3d Cir. 2023) (same); see Innogenetics, N.V. v. Abbott 

Lab’ys, 512 F.3d 1363, 1371 (Fed. Cir. 2008) (“We review 

procedural issues not unique to patent law under regional 

circuit law.”). 

To be sure, “[t]he party presentation principle is supple, not ironclad,” and there are circumstances in which it 

may be appropriate for a court to take a “modest initiating 

role” in the shape of the litigation. Sineneng-Smith, 

590 U.S. at 376. But rendering a patent invalid on a basis 

not advanced by any party is not such a circumstance. 

One cornerstone of patent litigation lies in 35 U.S.C. 

§ 282, which provides that “[a] patent shall be presumed 

valid” and that “[t]he burden of establishing invalidity of a 

patent or any claim thereof shall rest on the party asserting such invalidity.” That statutory prescription mandates 

that the party asserting an invalidity defense must prove 

that defense by clear and convincing evidence. Microsoft 

Corp. v. I4I Ltd. P’ship, 564 U.S. 91, 95 (2011). It thus follows that, in a court proceeding, a patent is not found 

“valid.” See Panduit Corp. v. Dennison Mfg. Co., 810 F.2d 

1561, 1569 (Fed. Cir. 1987) (“It is neither necessary nor appropriate for a court to declare a patent valid.”) (citing 

Env’t Designs, Ltd. v. Union Oil Co. of Cal., 713 F.2d 693, 

699 n.9 (Fed. Cir. 1984)). Rather, when a patent owner 

prevails in the face of an invalidity defense or counterclaim, it merely means that the patent challenger has 

failed to carry its burden of establishing, in that particular 

case, invalidity by clear and convincing evidence. See id.

at 1569–70; accord Shelcore, Inc. v. Durham Indus., Inc., 

745 F.2d 621, 627 (Fed. Cir. 1984) (“A patent is not held 

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10 ASTELLAS PHARMA, INC. v. SANDOZ INC. 

valid for all purposes but, rather, not invalid on the record 

before the court.”). By statute then, the court’s role in issues of patentability is straightforward. It “does not require [the court] to conclude whether something was or was 

not ‘invented’, or whether the court subjectively considers 

the invention ‘worthy’ of patent protection.” Lindemann 

Maschinenfabrik GMBH v. Am. Hoist & Derrick Co., 

730 F.2d 1452, 1457 n.1 (Fed. Cir. 1984). Rather, the 

court’s role is simply “to determine whether the patent’s 

challenger carried the burden of establishing invalidity.” 

Id.

Here, the district court appears to have misapprehended its role in adjudicating the issue of patentability. 

It interpreted Astellas’s “zealous defense” on issues of § 112 

as “conced[ing] that the ’780 patent is enabled because it 

claims invalid subject matter: a natural law applied via 

routine, conventional, and well-known methods.” Decision

at *1. It then used that “concession” to hold the patent invalid on a ground never advanced by Sandoz. That was an 

abuse of discretion. Curiously, the district court did appear 

to appreciate that the issue of patent eligibility was not asserted by Sandoz. In its denial of Sandoz’s Rule 52(b) motion, the court acknowledged Sandoz’s “worry [that] the 

parties inadequately raised the matter of subject-matter eligibility at trial or in briefing.” Rule 52(b) Decision, 

J.A. 8512. But it deemed that worry unwarranted because

of the “fundamental flaw” it sensed “in the [parties’] assertion that patent litigants may, in essence, consent around 

the bounds of patent eligibility.” Id. And therein lies the 

problem. It is for the parties—not the court—to chart the 

course of the litigation. See Lannom Mfg. Co. v. U.S. Int’l 

Trade Comm’n, 799 F.2d 1572, 1579 (Fed. Cir. 1986) (“It is 

beyond cavil that a district court does not have authority 

to invalidate a patent at its own initiative if validity is not 

challenged by a party.”).

Further, the district court’s treatment of patent eligibility suffered from its own “fundamental flaw.” It appears 

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ASTELLAS PHARMA, INC. v. SANDOZ INC. 11

that the district court believed patent eligibility under 

35 U.S.C. § 101 to be a threshold inquiry that it had a duty 

to address—even in the silence of the parties—akin to, for 

example, subject-matter jurisdiction. But the presumption 

of validity afforded to patents under § 282 applies equally 

to all grounds of validity, including the eligibility of the 

claimed subject-matter. Cellspin Soft, Inc. v. Fitbit, Inc., 

927 F.3d 1306, 1319 (Fed. Cir. 2019) (“Th[e] presumption 

reflects the fact that the Patent and Trademark Office has 

already examined whether the patent satisfies ‘the prerequisites for issuance of a patent,’ including § 101.” (quoting 

Microsoft, 564 U.S. at 95–96)).2 Accordingly, to the extent 

the district court believed that validity under § 101 is 

treated any differently than validity under §§ 102, 103, and 

112 for purposes of the party presentation principle, that 

was error.

Sandoz’s attempts to excuse the district court’s departure from that principle are unavailing. In its view, the 

district court acted within its authority in light of precedent and Astellas’s “stunning admissions” at trial regarding the invention. Sandoz Br. 23. Relying on cases from 

the late 1800s and certain non-binding out-of-circuit 

cases,3 Sandoz argues that “[t]he Supreme Court has long 

2 To be sure, § 101 is a threshold inquiry in obtaining 

patent protection. See In re Comiskey, 554 F.3d 967, 973 

(Fed. Cir. 2009) (explaining, in the context of patent prosecution, that “[o]nly if the requirements of § 101 are satisfied is the inventor allowed to pass through to the other 

requirements for patentability, such as novelty under § 102 

and . . . non-obviousness under § 103” (internal quotation 

marks and citation omitted)).

3 Sandoz also relies on Comiskey for the proposition 

that the Federal Circuit has “considered § 101 issues without prompting from the parties.” Sandoz Br. 20–21. 

Comiskey was an appeal from a decision of the Board of 

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12 ASTELLAS PHARMA, INC. v. SANDOZ INC. 

held that a court may consider the eligibility or validity of 

a patent, even if such a defense is not raised by the defendant in the action.” Id. at 18 (citing Slawson v. Grand Street, 

P.P & F.R. Co., 107 U.S. 649, 652 (1883); Brown v. Piper, 

91 U.S. 37, 43–44 (1875); Dunbar v. Myers, 94 U.S. 187, 

188 (1876)); see id. at 19–20 (citing Barkeij v. Lockheed Aircraft Corp., 210 F.2d 1, 1 (9th Cir. 1954); Howes v. Great 

Lakes Press Corp., 679 F.2d 1023, 1028 (2d Cir. 1982)). But 

those decisions were rendered before, or did not address the 

impact of, the Patent Act of 1952’s codification of a patent’s 

presumption of validity and the requirement that a patent 

challenger affirmatively plead its defenses. See Pub. L. No. 

82-593, § 282, 66 Stat. 792, 812 (1952) (codified at 

35 U.S.C. § 282). We therefore find Sandoz’s reliance on 

those cases unpersuasive.4

Patent Appeals and Interferences (“Board”), determining

that a patent application was unpatentable under § 103. 

554 F.3d at 969. We affirmed the Board’s judgment of unpatentability under § 101. Id. While neither the examiner 

nor the Board had made a patentability determination under § 101, we confirmed that both the APA and the Supreme Court’s decision in SEC v. Chenery Corp., 318 U.S. 

80 (1943), “made clear that a reviewing court can (and 

should) affirm an agency decision on a legal ground not relied on by the agency if there is no issue of fact, policy, or 

agency expertise.” Id. at 974 (emphases added). The APA 

and Chenery principles that existed in Comiskey do not exist in the present case.

4 For the first time at oral argument, Sandoz argued 

that it did plead an invalidity defense under § 101, referencing each Defendant-Appellee’s answer to Astellas’s 

complaint. See Oral Arg. at 16:42–57, available at

https://oralarguments.cafc.uscourts.gov/default.aspx?fl=23

-2032_08072024.mp3 (counsel for Sandoz arguing that 

“[t]he answers contain affirmative defenses under § 101, 

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ASTELLAS PHARMA, INC. v. SANDOZ INC. 13

Sandoz’s invocation of public policy to justify the district court’s decision is no more persuasive. Sandoz 

Br. 23–24 (arguing that the “public has a strong interest in 

the elimination of invalid pharmaceutical patents that delay or deter low-cost generic alternatives”). That argument 

is entirely irrelevant to the scope of a court’s authority to 

stray from the case as designed by the parties. Indeed, we 

have long rejected such “public responsibility” concerns in 

favor of adherence to the party presentation principle. See 

Lannom Mfg., 799 F.2d at 1579 (rejecting argument that 

the International Trade Commission has a public responsibility to “verify the validity of any patent brought before 

it”).

Accordingly, because the district court abused its discretion in holding the asserted claims invalid under 

35 U.S.C. § 101, a ground not invoked by Sandoz, we vacate 

the judgment and remand for adjudication of the issues 

properly raised and adequately supported by the record. 

Those issues are limited to infringement and validity under 

35 U.S.C. § 112. See J.A. 6591–93.

II

We turn now to Astellas’s request that this case be reassigned to a different district court judge on remand. Astellas argues that “[t]aken together, the district court’s two 

post-trial decisions are rather extraordinary,” Astellas 

Br. 55, such that reassignment is necessary to maintain an 

appearance of impartiality and fairness in the forthcoming 

remand proceedings.

and Lupin’s [counterclaim] has an express statement under § 101”). Sandoz did not raise that argument anywhere 

on appeal. Thus, it is forfeited. See Becton Dickinson & 

Co. v. C.R. Bard, Inc., 922 F.2d 792, 800 (Fed. Cir. 1990)

(noting we have discretion to consider arguments not 

raised in a party’s appellate brief).

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14 ASTELLAS PHARMA, INC. v. SANDOZ INC. 

Reassignment is “an exceptional remedy, one that we 

weigh seriously and order sparingly.” United States v. Kennedy, 682 F.3d 244, 258 (3d Cir. 2012); see Lazare Kaplan 

Int’l, Inc. v. Photoscribe Techs., Inc., 714 F.3d 1289, 1298 

(Fed. Cir. 2013) (providing that reassignment requests are 

evaluated “under the law of the regional circuit in which 

the district court sits”). When reviewing requests for reassignment, the Third Circuit applies “a standard that calls 

for reassignment when a reasonable person, with 

knowledge of all the facts, would conclude that the judge’s 

impartiality might reasonably be questioned.” Arrowpoint 

Cap. Corp. v. Arrowpoint Asset Mgmt., LLC, 793 F.3d 313, 

329 (3d Cir. 2015) (internal quotation marks and citations 

omitted). Having considered the parties’ arguments and

having undertaken our own review of the district court proceedings, we decline to order the extraordinary remedy of 

reassignment in this case.

Astellas first argues that the district court’s failure to 

abide by the party presentation principle is, “standing 

alone,” enough to warrant reassignment. See Astellas Br. 

55–56. We disagree. The Third Circuit has made clear that 

“adverse rulings—even if they are erroneous—are not in 

themselves proof of prejudice or bias” that warrant judicial 

reassignment. Arrowpoint, 793 F.3d at 330. We have already concluded that the district court abused its discretion, as a matter of procedure, in rendering its judgment. 

And, although we have serious doubts that, on the merits,

the asserted claims—directed to nonnatural compositions 

of matter and associated methods of use—are ineligible for 

patent protection (an issue we decline to resolve), those 

kinds of errors, i.e., errors relating to the propriety of the 

district court’s analysis, are insufficient to warrant reassignment.

Astellas next points to various statements that the district court made in its two decisions on appeal as evidencing judicial bias. For example, in its denial of Sandoz’s 

Rule 52(b) motion, the district court stated that “[t]he 

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ASTELLAS PHARMA, INC. v. SANDOZ INC. 15

pharmaceutical industry, to put it mildly, has perverted 

th[e] intent [of the Hatch-Waxman Amendments]. With 

alarming regularity since, brand and generic drug manufacturers have colluded to protect weak or invalid patents 

and share in the startling profits.” Rule 52(b) Decision, 

J.A. 8513 (citing an unrelated antitrust litigation concerning the sale of a type 2 diabetes drug). The district court

further stated that this “case is about the pharmaceutical 

industry’s long-standing ‘innovation’ of patenting extended-release formulas for soon-to-expire active-ingredient patents,” a practice the district court believes the U.S. 

Patent and Trademark Office has “accommodated” by issuing patents to such inventions. Id.

We agree with Astellas that these statements have no

relevance to the proceedings in this case, which are limited 

to the issues of infringement and validity under 35 U.S.C. 

§ 112 of three claims of the ’780 patent. We further understand Astellas’s concern that the district court’s commentary may evidence a personal frustration with the 

pharmaceutical industry as a whole. See also Sandoz Br. 

43 (“And to the extent that the district court’s opinions expressed a frustration with the pharmaceutical industry, 

both ‘brand and generic manufacturers’ were mentioned.”). 

To be sure, these proceedings are not an appropriate venue

for those frustrations to be aired, let alone acted upon. See 

Sineneng-Smith, 590 U.S. at 376 (“[Courts] do not, or 

should not, sally forth each day looking for wrongs to 

right.” (internal quotation marks and citation omitted)).

Although we have concerns with the analysis of the district court, we are not convinced that the judge, who has

overseen nearly two hundred patent cases and has ruled in 

favor of both innovative and generic manufacturers alike,

cannot resolve the outstanding issues impartially and 

fairly, particularly now that we have clarified the proper 

course for adjudication. Significantly, other than the 

court’s two rulings, Astellas cannot identify any instance 

in the life of this nearly four-year-old litigation in which 

Case: 23-2032 Document: 90 Page: 15 Filed: 09/18/2024
16 ASTELLAS PHARMA, INC. v. SANDOZ INC. 

the district court judge acted in a way that called into question his ability to do just that. Further, as Sandoz points 

out, the district court judge is currently presiding over two 

related cases that concern the same or similar validity issues on similar subject matter. See Sandoz Br. 48 n.6.

Ultimately, we trust that, upon remand, the district 

court can and will take an objective, measured, and thorough look into the legal issues and evidence of record to 

resolve only those disputes that exist between the parties. 

CONCLUSION

We have considered the parties’ remaining arguments 

and find them unpersuasive. For the reasons set forth 

above, we vacate the district court’s judgment and remand 

for adjudication of the case as it was shaped by the parties.

VACATED AND REMANDED

COSTS

No costs.

Case: 23-2032 Document: 90 Page: 16 Filed: 09/18/2024