United States Court of Appeals 

for the Federal Circuit ______________________

ENDO PHARMACEUTICALS INC., 

MALLINCKRODT LLC,

Plaintiffs-Appellees

v.

ACTAVIS LLC, FKA ACTAVIS INC., ACTAVIS 

SOUTH ATLANTIC LLC, TEVA 

PHARMACEUTICALS USA, INC.,

Defendants-Appellants

______________________

2018-1054

______________________

Appeal from the United States District Court for the 

District of Delaware in No. 1:14-cv-01381-RGA, Judge 

Richard G. Andrews.

______________________

Decided: May 3, 2019

______________________

MARTIN JAY BLACK, Dechert LLP, Philadelphia, PA, argued for plaintiffs-appellees. Also represented by SHARON 

K. GAGLIARDI; BLAKE GREENE, Austin, TX; JONATHAN 

LOEB, Mountain View, CA; ROBERT RHOAD, Princeton, NJ. 

 JEFFREY J. TONEY, Kasowitz, Benson, Torres & Friedman LLP, Atlanta, GA, for plaintiff-appellee Mallinckrodt 

LLC. Also represented by RODNEY R. MILLER, PAUL 

GUNTER WILLIAMS. 
2 ENDO PHARM. INC. v. ACTAVIS LLC

 JOHN C. O'QUINN, Kirkland & Ellis LLP, Washington, 

DC, argued for defendants-appellants. Also represented by 

WILLIAM H. BURGESS; CHARLES A. WEISS, ERIC H. YECIES, 

Holland & Knight, LLP, New York, NY. 

 ______________________

Before WALLACH, CLEVENGER, and STOLL, Circuit Judges.

Opinion for the court filed by Circuit Judge WALLACH.

Dissenting opinion filed by Circuit Judge STOLL.

WALLACH, Circuit Judge.

Appellees Endo Pharmaceuticals Inc. (“Endo Pharmaceuticals”) and Mallinckrodt LLC (“Mallinckrodt”) (collectively, “Endo”) sued Appellants Actavis LLC, Actavis South 

Atlantic LLC, and Teva Pharmaceuticals USA, Inc. (collectively, “Actavis”) in the U.S. District Court for the District 

of Delaware (“District Court”), alleging that two Abbreviated New Drug Applications filed by Actavis infringed

claims 1–6 (“the Asserted Claims”) of Mallinckrodt’s U.S. 

Patent No. 8,871,779 (“the ’779 patent”), which Endo Pharmaceuticals licenses. The District Court held that Actavis 

failed to “prove[] by clear and convincing evidence that any 

of the [A]sserted [C]laims . . . were invalid” as obvious or 

anticipated, Endo Pharm. Inc. v. Actavis Inc., No. 14-1381-

RGA, 2017 WL 3731001, at *1 (D. Del. Aug. 30, 2017), and 

entered final judgment of infringement, based on a stipulation by Actavis, J.A. 1. 

Actavis appeals, challenging the invalidity determination. We have jurisdiction pursuant to 28 U.S.C. 

§ 1295(a)(1) (2012). We affirm. 

BACKGROUND

I. The ’779 Patent

Entitled “Process for Preparing Morphinan-6-One 

Products with Low Levels of α,β-Unsaturated Ketone 
ENDO PHARM. INC. v. ACTAVIS LLC 3

Compounds,” the ’779 patent generally relates to compounds known as “morphinan alkaloids,” such as “oxymorphone,” which have “great medical importance” and 

“are used extensively for pain relief.” ’779 patent col. 1 ll. 

24–30. “Morphinan compounds and analogs thereof typically have a ring structure . . . corresponding to Formula 

(1)”:

Id. col. 1 ll. 38–53. “[P]harmaceutically desirable 

morphinan compounds” often “have a ketone group[1] on 

the C-ring of Formula (1) and a saturated bond[, i.e., single 

bond,] between the two carbon atoms positioned α and β to 

the ketone on the C-ring.” Id. col. 2 ll. 21–24. “[T]hese 

compounds may be referred to as morphinan-6-one compounds.” Id. col. 2 ll. 28–29. “[T]he ketone is present on 

the C(6) carbon atom, with the α and β carbon atoms being 

the C(7) and C(8) positions . . . .” Id. col. 2 ll. 25–26. 

In describing the prior art, the ’779 patent explains 

that “[v]arious processes for producing morphinan-6-one 

 

1 A ketone comprises “a carbonyl group”— an oxygen 

atom double-bonded to a carbon atom—where the carbon 

atom of the carbonyl group is single-bonded to two carbon 

atoms. J.A. 2952 (testimony of Actavis’s expert). 
4 ENDO PHARM. INC. v. ACTAVIS LLC

compounds are known,” and “many . . . involve some form 

of catalytic hydrogenation[2] of α,β-unsaturated ketone intermediate compounds [(‘ABUKs’)],” i.e., applying catalytic 

hydrogenation to compounds containing ketone groups 

with double bonds between the α and β carbon atoms to 

convert the double bonds to single bonds. Id. col. 2 ll. 29–

32. However, “[ABUKs] may persist as impurities in the 

final products.” Id. col. 2 ll. 43–45. These hydrogenation 

processes also “may tend to undesirably reduce the ketone[, 

a key functional part of morphinan-6-one compounds,] as 

well as reducing or removing the α,β-unsaturation.” Id. col. 

2 ll. 47–48. 

The ’779 patent discloses “processes for preparing 

highly pure morphinan-6-one products” having a relatively 

low concentration of ABUKs present as impurities, which

“involve treating a reaction mixture including a 

morphinan-6-one compound and an [ABUK] with a sulfurcontaining compound.” Id. col. 5 ll. 6–10. These processes

can “effectively reduce[] the concentration of undesirable 

[ABUKs] to acceptable levels,” id. col. 5 ll. 11–13, with the 

process employing a sulfur-containing compound that can 

reduce ABUK concentration “from levels of about 0.5% (by 

weight) or more to levels of not more than about 0.1% . . . , 

or lower (e.g., about 0.01% . . . , about 0.001% . . . , or 

 

2 Generally, catalytic hydrogenation is a process by 

which hydrogen, along with a catalyst, is added to a compound containing double bonds, i.e., an unsaturated compound, to convert it to a compound containing single bonds, 

i.e., a saturated compound. See J.A. 2993–94 (testimony of 

Actavis’s expert). A “catalyst activates the hydrogen,” and 

“[t]he hydrogen adds a double bond and takes a molecule 

that has a double bond and one hydrogen on each carbon to 

a single bond with two hydrogens on each carbon.” 

J.A. 2993.
ENDO PHARM. INC. v. ACTAVIS LLC 5

lower), with minimal side reactions, ketone reduction, 

and/or any other undesirable effects,” id. col. 5 ll. 17–22. 

The Asserted Claims recite:

1. A hydrochloride salt of oxymorphone comprising 

less than 0.001% of 14-hydroxymorphinone.[3]

2. The hydrochloride salt of claim 1 comprising less 

than 0.0005% of 14-hydroxymorphinone.

3. A pharmaceutical acceptable form comprising 

the oxymorphone hydrochloride according to 

claim 1.

4. A hydrochloride salt of a morphinan-6-one compound corresponding to Formula (2):

 

3 Relevant to this appeal, 14-hydroxymorphinone, 

also referred to as “oxymorphone ABUK,” is an ABUK impurity in oxymorphone and “is considered a precursor to 

oxymorphone because it can be made into oxymorphone by 

adding a hydrogen, resulting in a single bond.” Endo, 2017 

WL 3731001, at *1; see id. at *2. In turn, 14-hydroxycodeinone is an ABUK impurity in oxycodone and referred to 

as “oxycodone ABUK.” Id. at *8. 
6 ENDO PHARM. INC. v. ACTAVIS LLC

comprising less than 0.001% measured by 

[high performance liquid chromatography]

of an [ABUK] corresponding to Formula

(3):

wherein the morphinan-6-one compound is 

oxymorphone and wherein X is —N(R17)—;

R1 and R2 are hydrogen;

R3 is hydroxy;

R10 is hydrogen;

R14 is hydroxy; and
ENDO PHARM. INC. v. ACTAVIS LLC 7

R17 is methyl. 

5. The hydrochloride salt of claim 4 comprising less 

than 0.0005% of 14-hydroxymorphinone. 

6. A pharmaceutical formulation comprising the 

oxymorphone hydrochloride according to claim 4. 

Id. col. 37 l. 58–col. 38 l. 61 (emphases added). 

II. Prior Art References

The District Court determined three references constitute the prior art in this case. See Endo, 2017 WL 3731001, 

at *6–8. We present each in turn. 

A. Weiss

A scientific article from 1957, see Ulrich Weiss, Derivatives of Morphine. II. Demethylation of 14-Hydroxycodeinone. 14-hydroxymorphinone and 8,14-

Dihydroxydihydromorphinone, 22 J. Organic Chemistry 

1505, 1505–08 (1957) (“Weiss”) (J.A. 2295–98), discloses, 

inter alia, the use of catalytic hydrogenation to convert oxymorphone ABUK to oxymorphone. See J.A. 2297 (employing palladium charcoal “as catalyst” and teaching arriving 

at the result of 14-hydroxydihydromorphinone, i.e., oxymorphone). Weiss also recounts 8,14-dihydroxy-7,8-dihydromorphinone (“oxymorphone diol”) as “the product of 

hydration of the double bond of [oxymorphone ABUK],” 

J.A. 2295, the “ready conversion of [oxymorphone ABUK] 

into [oxymorphone diol],” J.A. 2296, and the reversion of 

oxymorphone diol to oxymorphone ABUK through the application of hydrochloride, see J.A. 2295, 2297. 

B. Chapman

Entitled “Process for Preparing Oxycodone Hydrochloride Having Less Than 25 [Parts Per Million (‘ppm’)] 14-

hydroxycodeinone,” U.S. Patent Application No. 

2005/0222188 (“Chapman”) (J.A. 2464–90) discloses, inter 

alia, processes that employ catalytic hydrogenation to 
8 ENDO PHARM. INC. v. ACTAVIS LLC

purify oxycodone ABUK into the salt form of oxycodone.

See J.A. 2473 (“In certain embodiments of the present invention, the 14-hydroxycodeinone [i.e., oxycodone ABUK] 

is converted to oxycodone by hydrogenation . . . in conjunction with a . . . catalyst . . . .”). Chapman recites processes

that convert oxycodone ABUK to 8,14-dihydroxy-7,8-dihydrocodeinone (“oxycodone diol”), a precursor to oxycodone 

ABUK, which can revert to oxycodone ABUK through the 

compound’s conversion to salt form and thereby frustrate

purification. See J.A. 2473–74. But Chapman provides a 

reaction that can remove oxycodone diol from a sample 

prior to the completion of purification, and prevent oxycodone diol’s reversion to oxycodone ABUK. See J.A. 2483–

84 (Example 3). 

C. Rapoport

A scientific article from 1967, see Henry Rapoport et 

al., The Synthesis of Thebaine and Northebaine from Codeinone Dimethyl Ketal, 89 J. Am. Chemical Soc’y 1942,

1942–47 (1967) (“Rapoport”) (J.A. 2908–13), discloses, inter alia, a process involving the use of bisulfite addition to 

convert oxycodone ABUK to oxycodone, see J.A. 2908–09. 

This process takes advantage of differences in solubility of

the products of reactions between bisulfites and oxycodone 

ABUK to separate oxycodone from oxycodone ABUK. See

J.A. 2908–09. 

DISCUSSION

Actavis contends that the District Court erred by, inter 

alia, (1) misconstruing the claim term 14-hydroxymorphinone, see Appellants’ Br. 67–74; and (2) determining that the Asserted Claims were not obvious in light of 

the prior art, see id. at 36–66. We address each argument 

in turn. 
ENDO PHARM. INC. v. ACTAVIS LLC 9

I. Claim Construction

A. Standard of Review and Legal Standard

“The proper construction of a patent’s claims is an issue 

of Federal Circuit law . . . .” Powell v. Home Depot U.S.A., 

Inc., 663 F.3d 1221, 1228 (Fed. Cir. 2011) (citation omitted). “[C]laim construction must begin with the words of 

the claims themselves.” Amgen Inc. v. Hoechst Marion 

Roussel, Inc., 457 F.3d 1293, 1301 (Fed. Cir. 2006) (citation 

omitted). “[W]ords of a claim are generally given their ordinary and customary meaning” that they “would have to 

a person of ordinary skill in the art [(‘PHOSITA’)] in question at the time of the invention.” Phillips v. AWH Corp.,

415 F.3d 1303, 1312–13 (Fed. Cir. 2005) (en banc) (internal 

quotation marks and citations omitted). The PHOSITA “is 

deemed to read the claim term not only in the context of 

the particular claim in which the disputed term appears, 

but in the context of the entire patent, including the specification.” Id. at 1313.4 Prosecution history may also be 

used to supply additional evidence of claim terms’ intended 

meaning. See Home Diagnostics, Inc. v. LifeScan, Inc., 381 

F.3d 1352, 1356 (Fed. Cir. 2004).5 “We review the district 

court’s evaluation of the patent’s intrinsic record during 

claim construction de novo.” Info-Hold, Inc. v. Applied Media Techs. Corp., 783 F.3d 1262, 1265 (Fed. Cir. 2015). 

While courts may consider extrinsic evidence in claim 

construction, “such evidence is generally of less 

 

4 “A specification includes both the written description and the claims of the patent.” Monsanto Tech. LLC v. 

E.I. DuPont de Nemours & Co., 878 F.3d 1336, 1341 (Fed. 

Cir. 2018) (internal quotation marks and citation omitted).

5 “The prosecution history . . . consists of the complete record of the proceedings before the [U.S. Patent and 

Trademark Office] . . . .” Phillips, 415 F.3d at 1317 (citation omitted).
10 ENDO PHARM. INC. v. ACTAVIS LLC

significance than the intrinsic record.” Wi-LAN, Inc. v. Apple Inc., 811 F.3d 455, 462 (Fed. Cir. 2016) (citation omitted). When, as here, “the district court . . . look[s] beyond 

the patent’s intrinsic evidence and . . . consult[s] extrinsic 

evidence,” such “factfinding must be reviewed for clear error.” Teva Pharm. USA, Inc. v. Sandoz, Inc., 135 S. Ct. 831,

841 (2015). “A factual finding is clearly erroneous if, despite some supporting evidence, we are left with the definite and firm conviction that a mistake has been made.” 

Profectus Tech. LLC v. Huawei Techs. Co., 823 F.3d 1375, 

1379 (Fed. Cir. 2016) (internal quotation marks and citation omitted). 

B. The District Court Properly Construed 14-Hydroxymorphinone as 14-Hydroxymorphinone Hydrochloride

The District Court, relying on intrinsic and extrinsic 

evidence, determined that a PHOSITA would understand 

the 14-hydroxymorphinone limitations stated in claims 1–

2 and 5 to mean “14-hydroxymorphinone hydrochloride,”

i.e., the “salt form” of 14-hydroxymorphinone. Endo, 2017 

WL 3731001, at *14 (internal quotation marks omitted). 

Actavis argues that this limitation requires no construction 

because of “[t]he plain language of the claims, and the undisputed chemical difference between 14-hydroxymorphinone [i.e., oxymorphone ABUK] and its 

hydrochloride salt.” Appellants’ Br. 67. We disagree with 

Actavis. 

The District Court correctly construed 14-hydroxymorphinone as 14-hydroxymorphinone hydrochloride. We 

begin with the claims. See Phillips, 415 F.3d at 1314. The 

Asserted Claims expressly employ the term 14-hydroxymorphinone three times, once each in claims 1–2 and 5. Independent claim 1 teaches “[a] hydrochloride salt of 

oxymorphone comprising” a certain amount of “14-hydroxymorphinone,” ’779 patent col. 37 ll. 58–59 (emphasis 

added), while claim 2, which is dependent on claim 1,

claims “[t]he hydrochloride salt of claim 1 comprising” a 
ENDO PHARM. INC. v. ACTAVIS LLC 11

lesser amount of “14-hydroxymorphinone,” id. col. 37 ll. 60–

61 (emphasis added). Claim 3, which is also dependent on 

claim 1, does not expressly use the term 14-hydroxymorphinone, but refers to the entire compound taught in 

claim 1 as “oxymorphone hydrochloride.” Id. col. 37 ll. 62–

63. In turn, claim 5 claims “[t]he hydrochloride salt of 

claim 4 comprising” a certain amount of “14-hydroxymorphinone.” Id. col. 38 ll. 58–59 (emphasis added). 

Therefore, the Asserted Claims only claim 14-hydroxymorphinone as part of the salt-, or hydrochloride-, form of 

the claimed compounds, and not as a separate non-salt, 

non-hydrochloride component. This indicates that, as used 

in the Asserted Claims, 14-hydroxymorphinone means 14-

hydroxymorphinone hydrochloride. 

Next, we turn to the broader specification. See Trs. of 

Columbia Univ. v. Symantec Corp., 811 F.3d 1359, 1363 

(Fed. Cir. 2016) (“The specification is always highly relevant to the claim construction analysis and is, in fact, the 

single best guide to the meaning of a disputed term.” (internal quotation marks, brackets, and citation omitted)). 

Relevant here, 14-hydroxymorphinone is mentioned in Example 3. See ’779 patent col. 37 l. 36. Example 3 recites 

that “an oxymorphone [hydrochloride] sample was treated 

with a sulfur-containing compound,” id. at col. 37 ll. 18–19, 

the sample having contained a certain amount of “14-hydroxymorphinone . . . impurity,” id. col. 37 ll. 24–25. Following treatment, “oxymorphone base” was filtered out, id.

col. 37 l. 31 (emphasis added), a sample of which contained, 

inter alia, “no detectable amount of 14-hydroxymorphinone,” id. col. 37 ll. 35–36. No distinction is made 

between the 14-hydroxymorphinone in the oxymorphone 

hydrochloride and oxymorphone base samples, but it is presented as part of these compounds, not as discrete compounds or as possessing a separate hydrochloride or base 

form. Nevertheless, 14-hydroxymorphinone’s use in the 
12 ENDO PHARM. INC. v. ACTAVIS LLC

broader specification is relatively unsupportive of either 

proffered construction.6 

Finally, we look to extrinsic evidence. See Phillips, 415 

F.3d at 1319 (allowing courts to look to extrinsic evidence 

to, inter alia, better understand the field of the invention 

and the meaning of a term to a PHOSITA). The District 

Court considered the testimony of Actavis’s expert, in 

which he “agree[d]” that a PHOSITA reading Example 3 of 

the ’779 patent “would have to assume that the ABUK impurity there was the ABUK oxymorphone [hydrochloride],” 

i.e., the salt form,” J.A. 3117; see Endo, 2017 WL 3731001, 

at *14, as is permitted, see Key Pharm. v. Hercon Labs. 

Corp., 161 F.3d 709, 716 (Fed. Cir. 1998) (“[T]rial courts 

generally can hear expert testimony for background and 

education on the technology implicated by the presented 

claim construction issues, and . . . have broad discretion in 

this regard.”). Indeed, Actavis’s expert acknowledged that,

“when you form[] the salt from a combination of the oxymorphone and the ABUK[, i.e., the 14-hydroxymorphinone], the [14-hydroxymorphinone] gets formed 

into a salt at the same time,” and that a “[PHOSITA] would 

be aware of that.” J.A. 3116; see J.A. 3413 (stating, by 

Endo’s expert, that a PHOSITA “would know that if you 

have oxymorphone ABUK in the form of 

a[] . . . salt, . . . then the ABUK will exist in the form of 

the . . . salt also”). Accordingly, the intrinsic and extrinsic

evidence support the District Court’s construction of 14-

 

6 Although we may also consider the prosecution history, see Home Diagnostics, 381 F.3d at 1356, neither the 

parties nor we have identified anything in the prosecution 

history that further elucidates the proper construction of 

this limitation, see generally Appellants’ Br.; Appellees’ Br.
ENDO PHARM. INC. v. ACTAVIS LLC 13

hydroxymorphinone as 14-hydroxymorphinone hydrochloride.7 

II. Obviousness

A. Standard of Review and Legal Standard

“Obviousness is a question of law, reviewed de novo, 

based upon underlying factual questions which are reviewed for clear error following a bench trial.” Pozen Inc. 

v. Par Pharm., Inc., 696 F.3d 1151, 1160 (Fed. Cir. 2012)

(internal quotation marks, italics, and citation omitted). A 

patent claim is invalid “if the differences between the subject matter sought to be patented and the prior art are such 

that the subject matter as a whole would have been obvious 

at the time the invention was made to a [PHOSITA].” 

35 U.S.C. § 103(a) (2006).8 Relevant underlying findings of 

 

7 Actavis’s argument that the Asserted Claims are 

anticipated by the prior art is dependent on our adopting 

their proffered construction of 14-hydroxymorphinone. See 

Appellants’ Br. 66–67, 74–75. Since we do not adopt Actavis’s construction, we need not address their anticipation 

argument. See Knowles Elecs. LLC v. Iancu, 886 F.3d 1369, 

1373 n.3 (Fed. Cir. 2018) (explaining that “we need not address the appellant’s conditional [invalidity] arguments” 

where the lower tribunal “did not err in its construction of 

[a] disputed limitation” (internal quotation marks, brackets, and citation omitted)). 8 Congress amended § 103 when it enacted the 

Leahy-Smith America Invents Act (“AIA”). Pub. L. No. 

112-29, § 3(c), 125 Stat. 284, 287 (2011). Likewise, Congress amended 35 U.S.C. § 102 through the AIA. See id.

§ 3(b), 125 Stat. at 285–87. However, because the application that led to the ’779 patent has never contained (1) a 

claim having an effective filing date on or after March 16, 

2013, or (2) a reference under 35 U.S.C. §§ 120, 121, or 

365(c) to any patent or application that ever contained such 
14 ENDO PHARM. INC. v. ACTAVIS LLC

fact include: (1) “the scope and content of the prior art,” 

(2) “differences between the prior art and the claims at issue,” (3) “the level of ordinary skill in the pertinent art,” 

and (4) the presence of objective indicia of nonobviousness 

such “as commercial success, long felt but unsolved needs, 

failure of others,” and unexpected results. Graham v. John 

Deere Co. of Kan. City, 383 U.S. 1, 17 (1966); see United 

States v. Adams, 383 U.S. 39, 50–52 (1966). “An obviousness determination requires finding that a [PHOSITA] 

would have been motivated to combine or modify the teachings in the prior art and would have had a reasonable expectation of success in doing so.” Regents of Univ. of Cal. 

v. Broad Inst., Inc., 903 F.3d 1286, 1291 (Fed. Cir. 2018) 

(citation omitted). 

B. The District Court Did Not Clearly Err in Finding a 

PHOSITA Would Not Have a Reasonable Expectation of 

Success in Combining the Prior Art

The District Court held that a PHOSITA “would have 

understood that it would not be feasible” to employ Chapman’s solution to the reappearing ABUK problem to 

Weiss’s catalytic hydrogenation process for oxymorphone. 

Endo, 2017 WL 3731001, at *9. The District Court also explained that a PHOSITA would not have a reasonable expectation of success in employing “sulfur addition and 

separation as a method of producing low-ABUK oxymorphone,” id., because Rapoport does not “teach[] that 

low-ABUK oxymorphone can be achieved through bisulfite 

addition combined with extraction,” id. at *10. The District 

Court also considered certain confidential communications 

between the U.S. Food and Drug Administration (“FDA”) 

and producers of oxymorphone, including Mallinckrodt 

 

a claim, the pre-AIA §§ 102 and 103 apply. See id. § 3(n)(1), 

125 Stat. at 293.
ENDO PHARM. INC. v. ACTAVIS LLC 15

(“FDA communications”). Id. at *12; see J.A. 2890–903.9 

The District Court held that the FDA communications did 

 

9 The FDA communications mandated that opioid 

manufacturers reduce ABUK impurities in oxycodone and 

oxymorphone to below 0.001%. J.A. 2895; see J.A. 2904. 

Although the District Court concluded that the FDA communications are not prior art, see Endo, 2017 WL 3731001, 

at *6–7, we disagree. The District Court determined that 

(1) “the documents [were not] generally available as required for them to be § 102(b) prior art,” id. at *6 (internal 

quotation marks and citation omitted); see 35 U.S.C. 

§ 102(b) (stating a patent may be invalid if “the invention 

was patented or described in a printed publication in this 

or a foreign country or in public use or on sale in this country, more than one year prior to the date of the application 

for patent in the United States”); and (2) “declar[ing] a desire to have a product that has a particular characteristic, 

but . . . [not] provid[ing] any teachings on how to achieve 

that goal,” is not enough to make a reference prior art under, inter alia, § 102(f), Endo, 2017 WL 3731001, at *6 n.4; 

see 35 U.S.C. § 102(f) (prohibiting the grant of a patent to 

one who “did not himself invent the subject matter sought 

to be patented”). However, we have stated that § 102(f)

“does not pertain only to public knowledge, but also applies 

to private communications between the inventor and another which may never become public.” OddzOn Prods., 

Inc. v. Just Toys, Inc., 122 F.3d 1396, 1401–02 (Fed. Cir. 

1997). Moreover, we have also provided that, “[u]nder an 

obviousness analysis, a reference need not work to qualify 

as prior art; it qualifies as prior art, regardless, for whatever is disclosed therein.” Geo. M. Martin Co. v. All. Mach. 

Sys. Int’l LLC, 618 F.3d 1294, 1302 (Fed. Cir. 2010) (internal quotation marks and citation omitted). Thus, confidentiality and the absence of any teachings of how to 

accomplish a stated goal do not bar the FDA communications from being considered prior art here. See id.; 
16 ENDO PHARM. INC. v. ACTAVIS LLC

not provide a reasonable expectation of success because 

they “were not teachings and provided no substantive information about how the companies were to go about producing low-ABUK oxymorphone” and instead “recognized 

the challenge the mandate posed for the companies.” Endo, 

2017 WL 3731001, at *12. Actavis challenges the District 

Court’s finding of a lack of reasonable expectation of success and argues the District Court’s conclusions “must be 

reversed.” Appellants’ Br. 66; see id. at 56–66. We disagree 

with Actavis.

The District Court did not clearly err in concluding that 

a PHOSITA would lack a reasonable expectation of success 

in combining Weiss, Chapman, and Rapoport. First, a 

PHOSITA would not have a reasonable expectation of success in employing Weiss’s catalytic hydrogenation process 

for oxymorphone with Chapman’s process to remove diol 

during hydrogenation. Although Weiss discloses a method 

of purifying oxymorphone ABUK through catalytic hydrogenation, it does not provide key reaction conditions, see 

J.A. 2295–98; see also J.A. 3456 (stating, by Endo’s expert, 

that Weiss “omits[, inter alia,] . . . the time that the hydrogenation reaction is run[,] . . . the amount and composition 

of the . . . catalyst[,] . . . precisely what catalyst [is] 

us[ed,] . . . [and] the pressure of the hydrogen gas,” each of 

which can “affect the effectiveness of the hydrogenation 

procedure”),10 or any level of achieved purification of 

 

OddzOn, 122 F.3d at 1401–02. As discussed below, the District Court considered the FDA communications in its reasonable expectation of success analysis and properly 

determined that they were insufficient. 

10 With regard to each prior art reference, the District 

Court, citing cognizable evidence, see, e.g., J.A. 3456 (testimony of Endo’s expert regarding Weiss), 3483 (same regarding Chapman), 3516 (same regarding Rapoport), found 

Endo’s expert “credible and more convincing” than 
ENDO PHARM. INC. v. ACTAVIS LLC 17

oxymorphone, let alone purification to the degree claimed 

by the Asserted Claims, see J.A. 2295–98; see also J.A. 3005 

(stating, by Actavis’s expert, that Weiss does not “measure 

[or] quantify the amount of ABUK[, i.e., 14-hydroxymorphinone]”), 3458–59 (same, by Endo’s expert); ’779 patent col. 37 l. 58–col. 38 l. 61 (claiming oxymorphone 

containing 10 ppm or less of 14-hydroxymorphinone). 

Weiss also explains that the catalytic hydrogenation process produces oxymorphone diol, see J.A. 2295–96, which is 

undesirable because it can revert to 14-hydroxymorphinone upon the process’ completion and thereby frustrate purification, see J.A. 3476–82 (describing, by Endo’s 

expert, how the process disclosed by Weiss produces oxymorphone diol, and how a significant amount of this diol is 

likely to revert to 14-hydroxymorphinone as a result of 

steps undertaken later in the process). With respect to the 

comparative effect of catalytic hydrogenation on oxymorphone ABUK and oxycodone ABUK, Weiss discloses 

that the former produces oxymorphone diol much more 

readily than the latter produces oxycodone diol, see

J.A. 2296 (explaining that the “ready conversion of [oxymorphone ABUK] into [oxymorphone diol] suggested the 

possibility” of a similar result in an oxycodone process, but 

finding “[t]he total yield of [oxycodone diol] obtained in this 

fashion was very small”), indicating that the process is 

much less effective on oxymorphone ABUK because oxymorphone diol can revert to oxymorphone ABUK and 

thereby hinder purification, see J.A. 3014 (explaining, by 

Actavis’s expert, that oxymorphone diol can “go[] to the undesired oxymorphone ABUK”), 3455 (stating, by Endo’s 

 

Actavis’s, see Endo, 2017 WL 3731001, at *9; see also id. at 

*8–11. We do not disturb these credibility findings on appeal. See Celsis in Vitro, Inc. v. CellzDirect, Inc., 664 F.3d 

922, 929 (Fed. Cir. 2012) (“The district court has wide discretion to weigh expert credibility. This court defers to 

such credibility determinations.” (citations omitted)).
18 ENDO PHARM. INC. v. ACTAVIS LLC

expert, that oxymorphone diol is a precursor to oxymorphone ABUK, and its presence can cause “ABUK levels . . . to increase after hydrogenation ends”). 

In turn, Chapman discloses processes involving the 

catalytic hydrogenation of oxycodone ABUK, see J.A. 2473, 

and that these processes create oxycodone diol, see 

J.A. 2470, which can hinder purification by “revert[ing] to 

some ABUK and build[ing] up ABUK after an attempted 

purification,” J.A. 3021. Chapman also describes a process 

that can reduce oxycodone diol in an oxycodone sample, see 

J.A. 2473–74, but Endo’s expert explained that this would 

likely be ineffective in achieving the same purity as the oxymorphone claimed by the Asserted Claims, see J.A. 3483–

91. This is because the only example of this process provided by Chapman, see J.A. 2383–84, discloses a “long reaction time” of “nearly 22 hours” only reducing the 

oxyocodone diol content of an oxycodone sample from 2,900 

ppm to 400 ppm, and “with 400 ppm [of diol], that’s a lot of 

ABUK you can make,” J.A. 3483. Moreover, the longer the 

reaction runs, the less diol is progressively removed and 

the more “other side reactions are going to come in and 

compete,” such that one would “start to hydrogenate other 

parts of the molecule and introduce other material” and, 

therefore, would not “have any [of the desired] product . . . left at all.” J.A. 3486–87; see ’779 patent col. 2 

ll. 46–51 (“[K]nown hydrogenation methods may tend to 

undesirably reduce the ketone as well as reducing or removing the [ABUK],” and “are not normally capable of efficiently and economically reducing the levels of [diol] to 

below 10 to 100 [ppm], or less.”). 

A PHOSITA would not have had a reasonable expectation of success in combining Weiss and Chapman because

Weiss disclosed a material difficulty with using catalytic 

hydrogenation to purify oxymorphone to the FDAmandated level, i.e., the production of relatively large 

amounts of oxymorphone diol, see J.A. 2295–96; see also

J.A. 3479 (explaining, by Endo’s expert, that a PHOSITA 
ENDO PHARM. INC. v. ACTAVIS LLC 19

would have understood Weiss to teach “that they’re going 

to have a higher concentration of the diol in the oxymorphone ABUK reactions than they will in the oxycodone 

and therefore there’s a higher chance that they’ll regenerate the oxymorphone ABUK after the end of the reaction 

than they would have in the oxycodone case”), and Chapman did not describe a viable solution to this difficulty, see

J.A. 3483 (explaining, by Endo’s expert, that a PHOSITA 

reading Chapman would not know how to achieve a sufficiently low amount of diol), 3486–87 (discussing, by Endo’s 

expert, the problem of hydrogenating too much of the molecule); see also J.A. 2473–74. Moreover, Endo’s expert testified that, because oxymorphone ABUK and oxycodone 

ABUK “are different molecules, . . . they are going to have 

different reactivities,” J.A. 3466; see J.A. 3220 (stating, by 

an inventor of another patent, that molecules like oxymorphone and oxymorphone ABUK can slow hydrogenation and are much less stable than oxycodone and 

oxycodone ABUK), and, therefore, a PHOSITA would have 

been unlikely to apply Chapman to oxymorphone ABUK, 

see J.A. 3445–46; see also J.A. 3455 (stating, by Endo’s expert, that the position that a PHOSITA would have utilized 

oxycodone ABUK purification methods on oxymorphone

ABUK “ignores differences between the reactivities of oxycodone and oxymorphone[,] . . . [and] trivializes the removal of the oxymorphone diol” and how “ABUK levels are 

expected to increase after hydrogenation ends”). 

Second, the District Court did not clearly err in finding 

that a PHOSITA lacked a reasonable expectation of success 

in employing Rapoport’s sulfur addition and separation 

process to remove oxymorphone impurities. Rapoport discloses a process for purifying oxycodone ABUK through the 

use of bisulfite additions, but it does not state that any resulting compounds have the purity levels of those in the 

Asserted Claims. See J.A. 2908–13. According to Endo’s 

expert, Rapoport explains that 25% of ABUK impurities remain following completion of the process, which is “not a 
20 ENDO PHARM. INC. v. ACTAVIS LLC

very good partition ratio.” J.A. 3516. In addition, he recounted that the process described by Rapoport not only 

fails to remove a significant amount of ABUK, but “result[s] in a large loss of the desired compound” as well. 

J.A. 3517. Therefore, he explained that a PHOSITA would 

not believe that Rapoport “would ever be able to get 

to . . . 10 [ppm],” as claimed in the ’779 patent. J.A. 3517; 

see J.A. 2911.

Third, based on the teachings of Weiss, Chapman, and 

Rapoport, the District Court did not clearly err in finding 

the FDA communications would not provide a PHOSITA 

with a reasonable expectation of success of achieving the 

claimed purity levels for oxymorphone. Relevant here, the 

FDA communications recount the FDA’s “processes for addressing the problem of impurities” in oxymorphone that 

had been determined to be mutagenic. J.A. 2893. The FDA 

limited ABUK content in oxymorphone to 0.001%, i.e., 10 

ppm, to satisfy FDA approval guidelines. See J.A. 2895; see 

also J.A. 2904 (providing that, in January 2004, “[the FDA] 

inform[ed] Mallinckrodt that a 0.001% limit [for ABUK] 

will be required for . . . oxymorphone”). The FDA communications introduced a market force incentivizing purification of oxymorphone to the level of the oxymorphone 

claimed by the Asserted Claims. See J.A. 2895; Plantronics, Inc. v. Aliph, Inc., 724 F.3d 1343, 1354 (Fed. Cir. 2013) 

(“[M]otivation to combine may be found explicitly or implicitly in[, inter alia,] market forces; design incentives; . . . any need or problem known in the field of 

endeavor at the time of invention . . . ; and the background 

knowledge, creativity, and common sense of [a PHOSITA].” 

(internal quotation marks and citation omitted)); see also

Allergan, Inc. v. Sandoz Inc., 726 F.3d 1286, 1291–92 (Fed. 

Cir. 2013) (“The potential for FDA approval . . . may 

properly be considered, . . . in determining whether [a 

PHOSITA] would be motivated to develop a drug product . . . .”). However, the FDA communications recite a goal 

without teaching how the goal is attained. See J.A. 2890–
ENDO PHARM. INC. v. ACTAVIS LLC 21

903; see also Innogenetics, N.V. v. Abbott Labs., 512 F.3d 

1363, 1373 (Fed. Cir. 2008) (“[K]nowledge of a problem and 

motivation to solve it are entirely different from motivation 

to combine particular references.”).11 Instead, the District 

Court found that the FDA communications “reveal that the 

FDA recognized the challenge the mandate posed for the 

companies.” Endo, 2017 WL 3731001, at *12. The FDA 

communications convey nothing that would have a led a 

PHOSITA to view Rapoport’s teachings in a different light, 

see J.A. 3517, or to believe that the sulfur process it describes might be more effective on oxymorphone ABUK, see 

J.A. 2890–903. Therefore, these communications would 

not have been enough to overcome the disclosures of Weiss, 

Chapman, and Rapoport, which indicate that a PHOSITA 

would not reasonably believe their disclosed methods were

fruitful avenues to achieve the FDA-mandated oxymorphone purity level. See Abbott Labs. v. Sandoz, Inc., 

544 F.3d 1341, 1352 (Fed. Cir. 2008) (stating, in the context 

of certain FDA regulations on extended-release 

 

11 Indeed, the District Court considered the FDA communications’ import in its motivation to combine or modify 

analysis. See Endo, 2017 WL 3731001, at *11–12. Actavis 

argues the District Court clearly erred in finding the FDA 

communications did not provide a motivation to combine 

the prior art. Appellants’ Br. 44. Even if the FDA communications provided a general motivation to the opioid industry to achieve a particular purity level, see Plantronics, 724 

F.3d at 1354, we need not resolve whether it provided the 

legally-required motivation to combine because we conclude that a PHOSITA would not have a reasonable expectation of success based on the prior art, see Intelligent BioSys., Inc. v. Illumina Cambridge Ltd., 821 F.3d 1359, 1367 

(Fed. Cir. 2016) (explaining that reasonable expectation of 

success and motivation to combine are “two different legal 

concepts”).
22 ENDO PHARM. INC. v. ACTAVIS LLC

formulations, that “knowledge of the goal does not render 

its achievement obvious”).12

This conclusion is further supported by the fact that 

the inventors of the ’779 patent engaged in extensive experimentation, involving much failure, to ultimately produce the oxymorphone of the Asserted Claims. See, e.g., 

J.A. 3142 (stating, by an inventor of the ’779 patent, that 

the inventors “tried many different” ways to achieve the 

oxymorphone of the purity claimed, “but none of [the prior 

art] tell[s] you which ones will get you below the FDAmandated level”), 3249–64 (describing, by a different inventor of the ’779 patent, a subset of the experiments engaged in to reach the purity of the claimed oxymorphone), 

3464 (acknowledging, by Endo’s expert, the “extensive experimentation” engaged in by the inventors of the ’779 patent to achieve the compounds claimed by the Asserted 

Claims). The inventors also testified to their concerns 

when they became aware of the FDA’s purity requirement 

because it represented a dramatic, and potentially problematic, change in light of then-current knowledge and capabilities. See, e.g., J.A. 3248 (expressing, by an inventor 

of the ’779 patent, that he “was fairly shocked and concerned” because “[10 ppm was] a fairly low number,” and 

 

12 The dissent raises the concern that, after the FDA 

imposed a purity requirement for oxymorphone, Endo improperly “claimed the FDA mandate[d]” purity levels, rather than “a specific process.” Dissent Op. 6; see id. (“This 

is not the type of innovation that the patent system and the 

obviousness standard were designed to protect.”). This policy issue does not bear on the legal issue of obviousness 

presented in this appeal. Instead, patent law allows a 

party like Endo to gain from its efforts by securing a patent

on a composition. See 35 U.S.C. § 101 (allowing “[w]hoever 

invents or discovers any new and useful . . . composition of 

matter” to “obtain a patent therefor”). 
ENDO PHARM. INC. v. ACTAVIS LLC 23

“[i]t represent[ed] a fundamentally significant paradigm

shift from the way the current [active pharmaceutical ingredient] manufacturing companies monitor and control 

their impurities”); see also J.A. 3386 (stating, by the project 

manager for Mallinckrodt’s project to lower ABUK content 

in opioids, that “[g]iven that the target level that we were 

asked to reach for the ABUK[] impurities was orders of 

magnitude lower than where we currently stood, there 

were a number of challenges on both the process chemistry 

side as well as the analytical chemistry side”). Thus, the 

District Court did not clearly err in finding no reasonable 

expectation of success.

Actavis argues, and the dissent accepts, that the District Court erred as a matter of law by imposing a heightened standard in its application of the reasonable 

expectation of success test. See Appellants’ Br. 56–57; Dissent Op. 2–4. We disagree. Although Actavis points to the 

District Court’s usage of the phrase “definitive solution,” 

Appellants’ Br. 56–57 (quoting Endo, 2017 WL 3731001, at 

*9),13 “[w]e will not find legal error based upon an isolated 

statement stripped from its context,” Waymo LLC v. Uber 

Techs., Inc., 870 F.3d 1350, 1361 (Fed. Cir. 2017) (internal 

quotation marks and citation omitted). Instead, the District Court articulated the proper legal standard, see Endo, 

2017 WL 3731001, at *6 (“That ‘expectation of success need 

only be reasonable, not absolute.’” (quoting Pfizer, Inc. v. 

Apotex, Inc., 480 F.3d 1348, 1364 (Fed. Cir. 2007))), and applied the correct standard, see, e.g., id. at *10 (explaining 

 

13 The dissent selectively chooses other statements 

made by the District Court. See Dissent Op. 3–4. Regardless, for the reasons explained, we are confident the District Court applied the correct standard. Indeed, we agree 

that, if the District Court had applied a ‘definitive solution’ 

or ‘actual success’ standard to measure reasonable expectation of success, it would be legal error. 
24 ENDO PHARM. INC. v. ACTAVIS LLC

that, for Rapoport’s sulfur addition and separation process, 

a PHOSITA would not understand “that this was a promising method” and stating a “single experiment on a different compound” was insufficient to render the process 

“obvious to a [PHOSITA]” (emphasis added)), *12 (finding 

“the FDA mandate [did not] provide[] a [PHOSITA] with a 

reasonable expectation of success” (emphasis added)). For 

instance, where the District Court stated that a PHOSITA 

“would not find a definitive solution in Chapman” to the 

diol problem, id. at *9, it did not solely base its finding on 

this statement. The District Court carefully surveyed each 

expert’s testimony on this issue, see id. at *8–9, found Actavis’s expert’s testimony “not credible in light of [Endo’s 

expert’s] explanation of what would happen,” and concluded that a PHOSITA “would have understood that it 

would not be feasible to simply run the reaction as [Actavis’s expert] suggested,” id. at *9. We do not find error 

in this reasoning. For the reasons stated above, the District Court did not commit clear error in finding that a 

PHOSITA lacked a reasonable expectation of success, such 

that the Asserted Claims would not have been obvious.14 

 

14 Actavis also argues that the District Court erred in 

its finding of non-obviousness because a secondary consideration, i.e., simultaneous invention, supports obviousness. 

See Appellants’ Br. 56. Actavis argues three patent applications and one patent close in time to the ’779 patent’s invention date, all of which disclose compounds of a purity 

comparable to those claimed by the Asserted Claims, support obviousness. See id. at 51–52. However, the three applications refer to formulations of oxycodone, not 

oxymorphone, see J.A. 2459–63 (U.S. Patent Application 

No. 2006/0111383, entitled “Preparation of Oxycodone”), 

2464–90 (Chapman), 2613–75 (U.S. Provisional Patent Application No. 60/557,492, entitled “Process for Preparing 

Oxycodone Substantially Free of 14-Hydroxycodeinone and 
ENDO PHARM. INC. v. ACTAVIS LLC 25

CONCLUSION

We have considered Actavis’s remaining arguments 

and find them unpersuasive. Accordingly, the Final Judgment of the U.S. District Court for the District of Delaware 

is 

AFFIRMED

 

Compositions Thereof”), and we agree with the District 

Court’s reasoning that the one successful purification of oxymorphone to the level of that claimed by the Asserted 

Claims, disclosed in the patent cited by Actavis, is unpersuasive with regard to obviousness, see Endo, 2017 WL 

3731001, at *12. 
United States Court of Appeals 

for the Federal Circuit ______________________

ENDO PHARMACEUTICALS INC., 

MALLINCKRODT LLC,

Plaintiffs-Appellees

v.

ACTAVIS LLC, FKA ACTAVIS INC., ACTAVIS 

SOUTH ATLANTIC LLC, TEVA 

PHARMACEUTICALS USA, INC.,

Defendants-Appellants

______________________

2018-1054

______________________

Appeal from the United States District Court for the 

District of Delaware in No. 1:14-cv-01381-RGA, Judge 

Richard G. Andrews.

______________________

STOLL, Circuit Judge, dissenting.

I respectfully dissent. The FDA set a regulatory requirement that ABUK content in oxymorphone products be 

less than 0.001% (10 ppm). Mallinckrodt then claimed this 

requirement in the ’779 patent. Not only does the FDA’s 

mandate disclose every limitation of claim 1, but it is the 

only prior art reference that discloses the 0.001% oxymorphone ABUK limitation. Compare J.A. 2736, 2895,

with ’779 patent col. 37 ll. 58–59. Yet, the district court determined that this mandate did not disclose “anything substantive relevant to obviousness.” Endo Pharm. Inc. v. 

Actavis Inc., No. CV-14-1381, 2017 WL 3731001, at *7 
2 ENDO PHARM. INC. v. ACTAVIS LLC

(D. Del. Aug. 30, 2017) (“Decision”). It further erred by imposing a requirement that a reference must teach how to 

solve a problem to provide a motivation to combine, conflating enablement and reasonable expectation of success requirements with motivation. See id. at *12. Finally, the 

district court applied an erroneously heightened standard 

for reasonable expectation of success by requiring a “definitive solution” and proof of actual success. Id. at *9. The 

majority would disregard a number of these errors as 

harmless, affirming on the lack of a reasonable expectation 

of success. Given the significance of the court’s errors, however, I cannot agree. While we owe deference to a district 

court’s factual findings, such deference is not due where 

the trial court applies the incorrect standard to arrive at 

those findings. I would vacate the district court’s decision 

and remand for a proper analysis under the correct legal 

standards. 

The district court found that the FDA Communications 

do not disclose how to achieve low-ABUK oxymorphone, 

“nor do they disclose that this result had ever been 

achieved in the past . . . . There is simply no disclosure of 

anything substantive relevant to obviousness in these communications.” Id. at *7. The district court further found 

that “[s]ince the FDA mandate was nothing more than a 

directive and provided no substantive teachings on how to 

produce low-ABUK oxymorphone, it cannot serve as a ‘motivation to combine’ in an obviousness analysis.” Id. at *12. 

I fail to see how the FDA Communications do not disclose 

“anything substantive relevant to obviousness,” when they 

disclose every limitation of claim 1 and are the only references that expressly disclose the limitation of oxymorphone 

ABUK content less than 0.001%. Id. at *7. It can hardly 

be disputed that the FDA communications motivated the 

actual development of the ’779 invention. Indeed, as one of 

the inventors of the ’779 patent testified, “no special attention was focused on” ABUK impurities prior to the FDA’s 

structural alert. J.A. 3138 at 222:19–21. 
ENDO PHARM. INC. v. ACTAVIS LLC 3

The district court also erred by elevating the reasonable expectation of success standard to require that the prior 

art provide a definitive solution to the problem and proof of 

actual success. For example, in addressing Rapoport, 

which discloses a sulfur addition reaction followed by extraction, the court required proof that Rapoport’s technique

was actually used and worked. Specifically, the district 

court found that a person of ordinary skill would not have 

thought Rapoport promising because of its poor extraction 

partition ratio combined with “the lack of any examples of 

this method being used successfully.” Decision, 2017 WL 

3731001, at *10 (emphasis added). This is the wrong 

standard. Had Rapoport disclosed successful use of sulfur 

addition and extraction to achieve ABUK levels of less than 

10 ppm, it would anticipate the claims. As we have repeatedly held, obviousness requires only a reasonable expectation of success, not proof of actual success. See PAR 

Pharm., Inc. v. TWI Pharm., Inc., 773 F.3d 1186, 1198 

(Fed. Cir. 2014). The district court further erred by requiring proof of actual success regarding Dr. Gokel’s proffered 

combination of Rapoport with conventional precipitation or 

chromatography. It discounted Dr. Gokel’s suggestion as 

“purely hypothetical,” stating that there “is no evidence anyone ever combined these methods prior to the invention 

date and Dr. Gokel himself never did any experiments to 

show that they would work.” Decision, 2017 WL 3731001,

at *10 (emphasis added). As mentioned above, obviousness 

does not require proof of successful use of a combination, 

and the court erred by requiring as much.

The district court may have recited the correct legal

standard, but contrary to what the majority states, the district court certainly did not apply that standard in its analysis. See Majority Op. 23–24. For example, the district 

court’s finding that a person of ordinary skill would not 

have found Rapoport “promising” was partially based on 

“the lack of any examples of [Rapoport] being used successfully.” Decision, 2017 WL 3731001, at *10. Further, the 
4 ENDO PHARM. INC. v. ACTAVIS LLC

district court noted that the Macfarlan Smith experiment—the “single experiment on a different compound”—

did not show ABUK reduction to below 0.001%. Id. In 

other words, there was no evidence that a sulfur addition

technique actually worked. As mentioned above, a reasonable expectation of success does not require proof of actual 

success. These statements are thus not examples of the 

district court applying the correct standard, as the majority

believes, and instead show the opposite. See Majority 

Op. 23–24.

The district court similarly erred when considering 

Chapman. After reviewing testimony from both experts, 

the district court credited Mallinckrodt’s expert, Dr. Davies, and stated that “even if a person of ordinary skill 

would view the oxycodone art as informative in researching 

possible solutions to reducing ABUK levels in oxymorphone, he would not find a definitive solution in Chapman.” Decision, 2017 WL 3731001, at *9 (emphasis added). 

This heightened requirement also goes beyond the reasonable expectation of success standard and constitutes legal 

error. Further, the district court’s finding that a person of 

ordinary skill “would have understood that it would not be 

feasible to simply run [Chapman’s] reaction to completion 

as Dr. Gokel suggested,” focuses on the wrong question. Id. 

It is not required for catalytic hydrogenation to be run to 

completion in order to achieve 10 ppm ABUK. In fact, 

Dr. Gokel testified that Chapman itself—which achieved 

5 ppm ABUK—was not run to completion: “Q: Now, did he 

run that part of the process to completion to convert the 

diol into the ABUK so he could then hydrogenate it and 

make the oxycodone drug? . . . A: He did not, but he could 

have.” J.A. 3019–20 at 103:22–104:6.

Finally, the district court erred by conflating the requirements of reasonable expectation of success and motivation to combine. The district court required that the 

FDA Communications teach how to achieve the claimed invention in order to provide a motivation to combine. See 
ENDO PHARM. INC. v. ACTAVIS LLC 5

Decision, 2017 WL 3731001, *12. Whether a reference 

teaches how to achieve the claimed invention speaks to enablement or reasonable expectation of success—entirely 

separate inquiries from motivation to combine. “[O]ne 

must have a motivation to combine accompanied by a reasonable expectation of achieving what is claimed in the patent-at-issue.” Intelligent Bio-Sys., Inc. v. Illumina 

Cambridge Ltd., 821 F.3d 1359, 1367 (Fed. Cir. 2016) (emphasis added). Motivation to combine refers to “a reason 

that would have prompted a person of ordinary skill in the 

relevant field to combine the elements in the way the 

claimed new invention does.” KSR Int’l Co. v. Teleflex Inc., 

550 U.S. 398, 418 (2007). A reasonable expectation of success, on the other hand, addresses whether a person of ordinary skill in the art would have understood that the 

proposed combination or modification would have been reasonably likely to be successful. See, e.g., UCB, Inc. v. Accord Healthcare, Inc., 890 F.3d 1313, 1325–26 (Fed. Cir. 

2018). 

Our case law does not require that a reference teach 

how to achieve the claimed invention in order to provide a 

motivation to combine. The FDA Communications disclose 

all the limitations of claim 1. They also disclose a reason 

to modify Weiss, Chapman, or Rapoport to achieve ABUK 

levels of less than 10 ppm: the FDA required such levels 

because it had determined that ABUK levels higher than 

10 ppm were genotoxic. If these communications also 

taught “how the goal is attained,” they would anticipate the 

asserted claims—we would have no need to address obviousness. 

For all these reasons, I would vacate the district court’s 

decision and remand to allow the district court to apply the 

correct obviousness test and properly consider the role of 

the FDA mandate—the sole reason for the ’779 patent’s existence—in the obviousness analysis. This is not a typical 

Hatch-Waxman case where the patentee provided the public with a new drug, formulation, or manufacturing process. 
6 ENDO PHARM. INC. v. ACTAVIS LLC

While Mallinckrodt’s patent specification is directed to a 

specific process for achieving the FDA’s objective, 

Mallinckrodt did not claim that process. Mallinckrodt instead claimed the FDA mandate. The FDA sought to make 

oxymorphone safer for the public and Mallinckrodt took advantage by claiming the directive itself, securing exclusive 

rights to a drug first approved in 1959. This is not the type 

of innovation that the patent system and the obviousness 

standard were designed to protect.