Amicus Curiae Brief — Cox Communications, Inc., et al., Petitioners v. Sony Music Entertainment, et al.

Supreme Court briefOct 22, 2025

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No. 24-171

IN THE

Supreme Court of the United States

COX COMMUNICATIONS, INC. AND COXCOM, LLC,

Petitioners,

SONY MUSIC ENTERTAINMENT, ET AL.,

Respondents.

On Writ of Certiorari to the

United States Court of Appeals

for the Fourth Circuit

BRIEF OF AMICUS CURIAE

PROF. BRUCE E. BOYDEN

IN SUPPORT OF RESPONDENTS

BRUCE E. BOYDEN

Counsel of Record

MARQUETTE UNIVERSITY LAW

SCHOOL

P.O. Box 1881

Milwaukee, WI 53201-1881

(414) 288-5492

bruce.boyden@marquette.edu

October 22, 2025

TABLE OF CONTENTS

TABLE OF AUTHORITIES ....................................... ii

INTEREST OF THE AMICUS ................................... 1

SUMMARY OF THE ARGUMENT ........................... 1

ARGUMENT ............................................................... 5

Contributory Infringement Liability in Copyright Law Should Be Guided by the Scope of

Aiding and Abetting Liability in Tort Law ......... 5

II. The Requisite Mental State for Both Contributory Infringement and Civil Aiding and

Abetting Is Knowledge ....................................... 10

III. The Requirement of “Material Contribution”

in Copyright Law Is Coextensive with “Substantial Assistance” in Tort Law ....................... 15

IV. The Jury Was Presented with Ample Evidence

to Conclude Cox Had Both Knowledge and

Provided Substantial Assistance ....................... 23

CONCLUSION.......................................................... 27

TABLE OF AUTHORITIES

Cases

Armstrong v. McAlpin,

699 F.2d 79 (2d Cir. 1983)..................................... 22

Bowker v. Dows,

3 F. Cas. 1070 (C.C.D. Mass. 1878) (No. 1,734) ... 14

Camp v. Dema,

948 F.2d 455 (8th Cir. 1991) ................................. 19

Capitol Records, Inc. v. MP3tunes, LLC,

821 F. Supp. 2d 627 (S.D.N.Y. 2011) .................... 16

Casey v. U.S. Bank N.A.,

127 Cal. App. 4th 1138 (2005) .............................. 19

Direct Sales Co. v. United States,

319 U.S. 703 (1943) ................................... 20, 21, 22

Failla v. City of Passaic,

146 F.3d 149 (3d Cir. 1998)................................... 10

Fonovisa, Inc. v. Cherry Auction, Inc.,

76 F.3d 259 (9th Cir. 1996) ............................... 6, 16

Fortnightly Corp. v. United Artists Television,

Inc., 392 U.S. 390 (1968) ......................................... 6

Gershwin Publ’g Corp. v. Columbia Artists

Mgmt., Inc., 443 F.2d 1159 (2d Cir. 1971) .......... 2, 6

Halberstam v. Welch,

705 F.2d 472 (D.C. Cir. 1983) ..................... 3, 16, 17

Harper v. Shoppell,

26 F. 519 (C.C.S.D.N.Y. 1886) .............................. 14

Harper v. Shoppell,

28 F. 613 (C.C.S.D.N.Y. 1886) .......................... 5, 14

iii

Inwood Labs., Inc. v. Ives Labs., Inc.,

456 U.S. 844 (1982) ......................................... 13, 23

Kalem Co. v. Harper Brothers,

222 U.S. 55 (1911) ................................................. 13

Keel v. Hainline,

331 P.2d 397 (Okla. 1958) ..................................... 22

Lawrence v. Dana,

15 F. Cas. 26 (C.C.D. Mass. 1869) (No. 8,136) ....... 5

Mendelsohn v. Cap. Underwriters, Inc.,

490 F. Supp. 1069 (N.D. Cal. 1979) ...................... 18

Metro-Goldwyn-Mayer Studios Inc. v. Grokster,

Ltd., 545 U.S. 913 (2005) .............................. 6, 7, 14

Perfect 10, Inc. v. Amazon.com, Inc.,

508 F.3d 1146 (9th Cir. 2007) ............................. 7, 8

Perfect 10, Inc. v. Visa Int’l Serv. Ass’n,

494 F.3d 788 (9th Cir. 2007) ....................... 8, 16, 21

Reilly v. Anderson,

727 N.W.2d 102 (Iowa 2006) ........................... 10, 12

Rosemond v. United States,

572 U.S. 65 (2014) ................................................. 11

Rosenthal & Co. v. Commodity Futures Trading

Comm’n, 802 F.2d 963 (7th Cir. 1986) ................. 10

Screen Gems–Columbia Music, Inc. v. Mark-Fi

Records, Inc., 256 F. Supp. 399 (S.D.N.Y. 1966) .... 6

Smith & Wesson Brands, Inc. v. Estados Unidos

Mexicanos, 605 U.S. 280 (2025) ............................ 20

Sony Corp. of Am. v. Universal City Studios, Inc.,

464 U.S. 417 (1984) ........................................... 7, 21

Ted Browne Music Co. v. Fowler,

290 F. 751 (2d Cir. 1923)......................................... 5

Thomson-Houston Elec. Co. v. Ohio Brass Co.,

80 F. 712 (6th Cir. 1897) ............................. 5, 14, 15

Twitter, Inc. v. Taamneh,

598 U.S. 471 (2023) ......................7, 9, 16, 17, 19, 24

United States v. Peoni,

100 F.2d 401 (2d Cir. 1938)..................................... 8

United States v. Thompson,

539 F. App’x 778, 779 (9th Cir. 2013) ................... 18

Wallace v. Holmes,

29 F. Cas. 74 (C.C.D. Conn. 1871) (No. 17,100) ..... 5

Woodward v. Metro Bank of Dallas,

522 F.2d 84 (5th Cir. 1975) ................................... 11

Statutes

17 U.S.C. § 512 .......................................................... 22

35 U.S.C. § 271(c) ...................................................... 14

Treatises

Dan B. Dobbs, Paul T. Hayden & Ellen M.

Bublick, Dobbs’ Law of Torts § 435

(2d ed. 2025) .......................................................... 11

Model Penal Code § 2.02 (A.L.I. 1985) ..................... 11

Melville B. Nimmer & David Nimmer,

Nimmer on Copyright (Oct. 2025) ..... 2, 7, 9, 12, 13,

............................................................. 14, 15, 16, 23

William F. Patry, Patry on Copyright (2025) ............. 9

Restatement (First) of Torts § 876 (A.L.I. 1939) ..... 16

Restatement (Second) of Torts § 290 (A.L.I. 1965) .. 12

Restatement (Second) of Torts § 302A

(A.L.I. 1965) ..................................................... 10, 11

Restatement (Second) of Torts § 302B

(A.L.I. 1965) ..................................................... 10, 11

Restatement (Second) of Torts § 876

(A.L.I. 1979) ..................................2, 9, 10, 11, 17, 18

Restatement (Second) of Torts § 877

(A.L.I. 1977) ....................................................... 6, 10

Restatement (Second) of Torts § 8A (A.L.I. 1965) ... 11

Restatement (Third) of Torts: Inten. Torts to

Persons § 10 (A.L.I., Tentative Draft

No. 3, 2018) .......................................... 12, 13, 17, 18

Restatement (Third) of Torts: Liab. for Econ.

Harm § 28 (A.L.I. 2020) .................10, 17, 18, 20, 24

Restatement (Third) of Torts: Misc. Provisions

§ 4_0 (A.L.I., Tentative Draft No. 3, 2024) ..... 10, 11

Restatement (Third) of Torts: Phys. & Emot.

Harm § 1 (A.L.I. 2010) .................................... 11, 12

Other Authorities

Mark Bartholomew & Patrick F. McArdle,

Causing Infringement, 64 Vand. L. Rev. 675

(2011) ....................................................................... 7

Nathan Isaac Combs, Note, Civil Aiding and

Abetting Liability, 58 Vand. L. Rev. 241 (2005) ... 11

Federal Civil Jury Instructions of the Seventh

Circuit 12.62 (2017)............................................... 24

2 Judicial Council of California Civil Jury

Instructions, CACI No. 3610 (2024) ..................... 24

Richard C. Mason, Civil Liability for Aiding and

Abetting, 61 Bus. Law. 1135 (2006) ........................ 8

Giles S. Rich, Infringement under Section 271 of

the Patent Act of 1952, 21 Geo. Wash. L. Rev.

521, 525 (1953) ........................................................ 5

Kenneth W. Simons, A Restatement (Third) of

Intentional Torts?, 48 Ariz. L. Rev. 1061 (2006) .. 11

Kenneth W. Simons, Statistical Knowledge

Deconstructed, 92 B.U. L. Rev. 1 (2012) ............... 13

Alfred C. Yen, Torts and the Construction of

Inducement and Contributory Liability in

Amazon and Visa, 32 Colum. J.L. & Arts 513

(2009) ....................................................................... 8

INTEREST OF THE AMICUS

Amicus is a professor of law who teaches and

writes about copyright law, including secondary liability. His sole interest is in the sound development of

SUMMARY OF THE ARGUMENT

This case presents the Court with an opportunity to

clarify a doctrine that has received only desultory formulation in the lower courts for more than a century.

The lack of explication has become increasingly problematic as lower courts have struggled with the question of how to apply contributory liability precedents

from the twentieth century to the fact patterns of today.

The answer is perhaps counterintuitive: secondary

infringement doctrine needs to return to its roots in

tort law. Courts have long recognized that copyright

infringement is a species of tort and have thus borrowed from tort principles to define secondary liability. Elaboration of the influential Gershwin test for

contributory infringement, which was applied below,

should follow the well-developed framework of civil

aiding and abetting liability in tort law. See Gershwin

1 No counsel for a party authored this brief in whole or in part,

and no person made a monetary contribution to the preparation

or submission of this brief other than the amicus. Amicus’s university affiliation is provided for contact purposes only; neither

Marquette University nor Marquette University Law School

have adopted any position on this case.

Pub’g Corp. v. Columbia Artists Mgmt., Inc., 443 F.2d

1159 (2d Cir. 1971); Pet. App. 20a-21a; Restatement

(Second) of Torts § 876(b) (A.L.I. 1979). The Gershwin

test already closely parallels aiding and abetting in its

basic outlines. Both require (1) knowledge of another’s

plan or pattern of tortious activity, and (2) material

contribution to—or synonymously, substantial assistance for—that activity. What tort law can provide

copyright is greater certainty as to the requisite mental state and a framework for determining when conduct does and does not provide “substantial assistance” (or “material contribution”).

First, tort law confirms the position taken in the

majority of contributory copyright infringement cases,

which is that knowledge is the required mental state

for defendants, not intent. See 4 Melville B. Nimmer

David

Nimmer,

Nimmer

§13E.03[B][2][a] (Oct. 2025) (Nimmer). Although the

cases are not uniform, tort law has settled on the same

position for aiding and abetting. See Restatement

(Second) of Torts § 876(b). A secondary actor may be

contributorily liable for infringement or a tort when

that actor knows that a particular third party’s conduct constitutes wrongdoing. The defendant need not

desire the infringing outcome or be substantially certain it will occur; knowledge of the infringer’s pattern

or plan is sufficient.

The knowledge standard is particularly appropriate for contributory liability because in both copyright

law and tort law it depends on the defendant’s prediction of future third-party conduct based on the third

party’s past statements or actions. Thus courts in both

realms have provided for liability based on the defendant’s having knowledge or reason to know of the third

party’s imminent wrongdoing. In both copyright and

tort, that knowledge must be based on either the fact

that the defendant’s assistance can only further

wrongdoing, or on facts learned about a particular person’s plan to engage in wrongdoing. Such knowledge

can be supplied by notice to the defendant, but only if

that notice is accompanied by other indicia of reliability, as was the case here.

Civil aiding and abetting law can do even more to

help clarify the “material contribution” requirement of

the Gershwin test. Rather than attempting to determine the existence of “direct connections” or “indispensability,” courts should instead consider the factors from Halberstam v. Welch, 705 F.2d 472 (D.C. Cir.

1983): the nature of the encouraged act, the amount

and kind of assistance, the defendant’s presence, the

relationship to the wrongdoer, the defendant’s state of

mind, and the duration of assistance. Id. at 483-84.

This more nuanced inquiry can better draw lines between necessary but insubstantial contributions to

wrongdoing and routine but significant contributions.

Where a business knows little about particular acts of

wrongdoing and supplies a product or service to the

general public that is widely used for legitimate purposes, substantial assistance will not be found. But

where the business has more targeted knowledge of

wrongdoing, and continues to supply a good or service

that importantly aids in that wrongdoing, substantial

assistance may exist.

The jury below received proper instructions on the

Gershwin test and ample evidence on both elements of

the test, even though knowledge had already been resolved on summary judgement. Indeed, both parties

presented evidence to the jury that covered all of the

Halberstam factors, some of it weighing in favor of

substantial assistance and some against. After twelve

days of trial, the jury sided with the plaintiffs. Its verdict of contributory liability should be affirmed, and

the Court should guide lower courts to look more to

common law tort principles in future contributory infringement cases.

ARGUMENT

Contributory Infringement Liability in Copyright Law Should Be Guided by the Scope

of Aiding and Abetting Liability in Tort Law

As courts have held since the nineteenth century,

Browne Music Co. v. Fowler, 290 F. 751, 754 (2d Cir.

1923); Lawrence v. Dana, 15 F. Cas. 26, 61 (C.C.D.

Mass. 1869) (No. 8,136); see also Wallace v. Holmes, 29

F. Cas. 74, 80 (C.C.D. Conn. 1871) (No. 17,100) (describing patent infringers as “tort-feasors”). Accordingly, courts deciding infringement cases have long

borrowed from tort law to delineate secondary liability

doctrines, including contributory infringement, even

in the absence of express statutory provisions. In one

early case, the court held that the seller of a printing

plate who knew it would be used for copyright infringement was liable for “acting in concert” with the

purchaser. Harper v. Shoppell, 28 F. 613, 615

(C.C.S.D.N.Y. 1886). A decade later, then-Judge Taft

similarly justified contributory liability for patent infringement as akin to the rule “[f]rom the earliest

times” of holding those who aid and abet a trespass

jointly liable. Thomson-Houston Elec. Co. v. Ohio

Brass Co., 80 F. 712, 721 (6th Cir. 1897); see also Giles

S. Rich, Infringement under Section 271 of the Patent

Act of 1952, 21 Geo. Wash. L. Rev. 521, 525 (1953).

In copyright law, contributory infringement ultimately received its canonical formulation in Gershwin

Publishing Corp. v. Columbia Artists Management,

Inc., 443 F.2d 1159 (2d Cir. 1971). Invoking ”the

common law doctrine that one who knowingly participates or furthers a tortious act is jointly and severally

liable with the prime tortfeasor,” the Gershwin court

identified two elements for contributory liability:

(1) “knowledge of the infringing activity;” and (2) “induc[ing], caus[ing], or materially contribut[ing] to the

infringing conduct of another.” Id. at 1162 (quoting

Screen Gems–Columbia Music, Inc. v. Mark-Fi Records, Inc., 256 F. Supp. 399, 403 (S.D.N.Y. 1966)). The

court provided little further elaboration of these elements other than quoting this Court’s statement in

Fortnightly Corp. v. United Artists Television, Inc.,

392 U.S. 390 (1968), that “mere quantitative contribution cannot be the proper test” for copyright liability;

rather, the defendant’s role in the activity must be

considered in context. Id. at 397.

Despite Gershwin’s reference to inducement and

causation, lower courts quickly reduced the second element to “material contribution.” See, e.g., Fonovisa,

Inc. v. Cherry Auction, Inc., 76 F.3d 259, 264 (9th Cir.

1996). This Court’s decision in Metro-Goldwyn-Mayer

Studios Inc. v. Grokster, Ltd., 545 U.S. 913 (2005), ultimately clarified that inducement of infringement

would also suffice for secondary liability. Id. at 930.2

Inducement, like civil conspiracy, requires the defendant to intend the accomplishment of a shared goal,

such as by agreement. See Restatement (Second) of

Torts § 877 cmt. a (A.L.I. 1979) (inducement liability

applies to intended result); Twitter, Inc. v. Taamneh,

2 Knowingly “causing” a copyright infringement through an

immaterial contribution has never been held to be sufficient for

contributory liability.

598 U.S. 471, 489–90 (2023) (civil conspiracy requires

agreement). The Grokster decision, however, did not

abandon the Gershwin framework, as evidenced by

the fact that Gershwin was cited approvingly in the

very same sentence that defined inducement, Grokster, 545 U.S. at 930. Grokster, like Sony before it,

“was never meant to foreclose rules of fault-based liability derived from the common law.” Id. at 934-35

(discussing Sony Corp. of Am. v. Universal City Studios, Inc., 464 U.S. 417 (1984)).

In recent years, courts have struggled to apply

Gershwin’s two elements to cases involving digital

technology. See Mark Bartholomew & Patrick F.

McArdle, Causing Infringement, 64 Vand. L. Rev. 675,

678 (2011) (Gershwin test “has fallen into analytic disrepair”). For example, some lower courts have looked

for evidence of intent in all contributory infringement

cases, not just those involving inducement. See Perfect

10, Inc. v. Amazon.com, Inc., 508 F.3d 1146, 1171 (9th

Cir. 2007) (basing contributory liability on “intentionally encouraging direct infringement [by] knowingly

tak[ing] steps that are substantially certain to result

in such direct infringement”). Other courts have instead held that actual or constructive knowledge is

sufficient. See 4 Nimmer § 13E.03[B][2][a] (Oct. 2025).

The Fourth Circuit decision below at times cited intent as the required scienter, and other times “actual

knowledge” of infringement. Compare Pet. App. 21a

(referring to “the intent necessary to prove contributory infringement”) with id. at 26a (referring to “actual knowledge”).

With respect to material contribution, lower

courts have reached varied conclusions on whether a

causal factor in infringement is “material.” In a pair

of cases in 2007, the Ninth Circuit struggled to explain

why linking to an infringing website in search results

could be a material contribution, but processing credit

card payments for such sites was not. Compare Amazon.com, 508 F.3d at 1172 (search engine “substantially assists” infringing sites find a worldwide market) with Perfect 10, Inc. v. Visa Int’l Serv. Ass’n, 494

F.3d 788, 796 (9th Cir. 2007) (payment processors

“have no direct connection” to infringement). In the

decision below, the Fourth Circuit cited the “indispensab[ility]” of Cox’s internet service and its failure to

address infringement—the sort of “quantitative contribution” that Fortnightly (and Gershwin) discouraged. Pet. App. 26a; see also Alfred C. Yen, Torts and

the Construction of Inducement and Contributory Liability in Amazon and Visa, 32 Colum. J.L. & Arts 513,

527 (2009) (noting that power companies also provide

essential services to infringers).

The path out of this swamp is to follow the more

detailed guide established for aiding and abetting liability in tort law. With roots extending back to the

fourteenth century, see United States v. Peoni, 100

F.2d 401, 402–03 (2d Cir. 1938), civil aiding and abetting liability has been explicated through three editions of the Restatement of Torts and has been recognized in some fashion in at least thirty states. See

Richard C. Mason, Civil Liability for Aiding and Abetting, 61 Bus. Law. 1135, 1139-40 (2006). The Gershwin formulation for contributory infringement is

strikingly similar to the elements of civil aiding and

abetting as they developed over the course of the twentieth century.3 First, Gershwin requires knowledge of

the infringing activity, just as aiding and abetting liability typically requires knowledge that a third party’s

conduct “constitutes a breach of duty.” Restatement

(Second) of Torts § 876(b) (A.L.I. 1979). Second, Gershwin requires material contribution to the infringing

activity—“material” meaning “important” rather than

“physical”—just as civil aiding and abetting liability

requires “substantial assistance.” See 4 Nimmer

§ 13E.03[B] (“[T]he contribution to the direct infringement must be substantial.”). Courts have over time developed a set of factors to help guide the inquiry into

whether a defendant has provided “substantial assistance,” but as this Court has recently held, the critical

determination is whether the defendant’s “participation in another’s wrongdoing … is both significant and

culpable enough to justify attributing the principal

wrongdoing to the aider and abettor.” Twitter, Inc. v.

Taamneh, 598 U.S. 471, 504 (2023).

Contributory infringement liability would therefore benefit from borrowing the framework elaborated

for aiding and abetting liability: a scienter of

knowledge of a third party’s infringing activity, and a

set of factors to help determine if a defendant’s

3 Contributory infringement has sometimes been described as

emerging from the much more recent concept of enterprise liability, but that is an error. See 6 William F. Patry, Patry on Copyright § 21:44 (2025) (refuting the connection).

contribution was material enough to justify attributing the direct infringer’s wrongdoing to the defendant.

II. The Requisite Mental State for Both Contributory Infringement and Civil Aiding and

Abetting Is Knowledge

Primary torts are commonly classified as intentional, negligent, or strict liability. Secondary tort liability, however, does not have to fit into this same

scheme. Some of it does; some secondary liability is intentional, see Restatement (Second) of Torts §§ 876(a)

(civil conspiracy), id. § 877(a) (inducement); some is

negligent, see Restatement (Second) of Torts §§ 302A,

302B (A.L.I. 1965) (negligent failure to take precautions against third-party torts); and some is strict liability, see Rosenthal & Co. v. Commodity Futures

Trading Comm’n, 802 F.2d 963, 966 (7th Cir. 1986)

(respondeat superior). But the fault underlying civil

aiding and abetting liability involves knowing assistance, not intent as typically defined in tort law. See

Restatement (Third) of Torts: Misc. Provisions § 4_0

reporters’ note d (A.L.I., Tentative Draft No. 3, 2024)

(“It is well-established that knowledge, but not intent,

is required for civil aiding and abetting liability.”); Restatement (Third) of Torts: Liab. for Econ. Harm § 28

cmt. c (A.L.I. 2020) (“[I]t need not be shown that the

defendant desired the tortious outcome.”).4 Nor does it

4 Criminal aiding and abetting may require a higher standard.

See Reilly v. Anderson, 727 N.W.2d 102, 114 (Iowa 2006); Failla

v. City of Passaic, 146 F.3d 149, 156-57 (3d Cir. 1998); Nathan

require the secondary actor’s breach of a duty, which

is the subject of other forms of liability. See Restatement (Second) of Torts §§ 302A, 302B, 876(c); see also

Restatement (Third) of Torts: Misc. Provisions § 4_0

cmt. d (“[A]iding and abetting liability cannot be classified as either an intentional or negligence tort.”);

Dan B. Dobbs, Paul T. Hayden & Ellen M. Bublick,

Dobbs’ Law of Torts § 435 (2d ed. 2025) (distinguishing

aiding and abetting from negligence-based liability).

Instead, as the Restatements and courts have made

clear, knowledge is “the clue to liability.” Woodward v.

Metro Bank of Dallas, 522 F.2d 84, 96 (5th Cir. 1975).

Knowledge is a state of mind that applies to factual

conditions, or what the Model Penal Code terms “circumstance” elements. Kenneth W. Simons, A Restatement (Third) of Intentional Torts?, 48 Ariz. L. Rev.

1061, 1093 n.110 (2006); Model Penal Code

§ 2.02(2)(b) (A.L.I. 1985). Intent, on the other hand,

refers in tort law “to the consequences of an act, rather

than the act itself.” Restatement (Second) of Torts §

8A cmt. a (A.L.I. 1965); see also Restatement (Third)

of Torts: Phys. & Emot. Harm § 1 (A.L.I. 2010).

While knowingly providing assistance to a tortfeasor is “intentional” in the sense that the secondary actor intends its own actions, it need not be intentional

Isaac Combs, Note, Civil Aiding and Abetting Liability, 58 Vand.

L. Rev. 241, 251 (2005). Even in criminal cases, the required state

of mind has been variously stated. See Rosemond v. United

States, 572 U.S. 65, 84-85 (2014) (Alito, J., concurring).

as to the consequences. For example, a passenger assisting a driver in taking a bong hit while driving is

aiding and abetting a tort, even if the passenger does

want the vehicle to crash and does not believe it will

happen. See Reilly v. Anderson, 727 N.W.2d 102, 11415 (Iowa 2006). Thus, the Fourth Circuit applied an

unnecessarily demanding standard in requiring plaintiffs below to show Cox’s “substantial[ ] certain[ty]”

that infringement would occur, which is a level of

knowledge as to consequences that substitutes for intent. Pet. App. 21a-22a; see Restatement (Third) of

Torts: Phys. & Emot. Harm § 1 cmt. c (belief insufficient for intentional torts). Knowledge, on the other

hand, requires only “consciousness of the existence of

a fact,” which can include a belief that the fact probably exists. Restatement (Second) of Torts § 290 cmt. b

(A.L.I. 1965).

Knowledge of the tortfeasor’s plan, as opposed to

substantial certainty of the result, is particularly appropriate for civil aiding and abetting and contributory infringement cases because, as the court below

recognized, such cases require a prediction as to what

a third party will do based on that person’s past statements and actions. See Pet. App. 22a; 4 Nimmer

§ 13E.03[B][3][a] (2025). In many cases, an aider and

abetter will only have information “that the primary

actor plans to commit [a tort] and that his or her own

actions might contribute to that tort.” Restatement

(Third) of Torts: Inten. Torts to Persons § 10 cmt. c

(A.L.I., Tentative Draft No. 3, 2018). Such knowledge

is sufficient even if the secondary actor lacks detailed

information about “the means by which the primary

actor will accomplish the tort or even the nature of the

eventual tort itself.” Id. reporter’s note cmt. c.

This Court has not directly considered the exact

state of mind required to establish contributory copyright infringement outside of the inducement context.

The “nice question[ ]” of whether “mere indifferent

supposition or knowledge” would be sufficient was left

open by this Court’s decision in Kalem Co. v. Harper

Brothers, 222 U.S. 55, 62 (1911). But this Court has

held that contributory trademark infringement lies

when “a manufacturer or distributor … continues to

supply its product to one whom it knows or has reason

to know is engaging in trademark infringement.” Inwood Labs., Inc. v. Ives Labs., Inc., 456 U.S. 844, 854

(1982). And the majority of lower courts have similarly

held that for copyright, knowledge, whether actual or

constructive, is enough. See 4 Nimmer §

13E.03[B][2][a] (standard “most frequently” stated as

“knew or had reason to know”).

That knowledge must in some way be targeted at

particular acts. To be contributorily liable, a defendant must know more than that, somewhere out there,

someone is almost certainly using its product or service to infringe. Cf. Kenneth W. Simons, Statistical

Knowledge Deconstructed, 92 B.U. L. Rev. 1, 24 (2012)

(low-risk activities do not become high-risk when aggregated). Rather, either the defendant’s product or

service must be good for nothing but infringement,

such that intent to assist infringement may be imputed, Metro-Goldwyn-Mayer Studios Inc. v. Grokster,

Ltd., 545 U.S. 913, 932 (2005), or the defendant must

know of a specific actor’s plan or pattern of infringement and contribute to it. See 4 Nimmer

§ 13E.03[C][1].

The latter form of knowledge will establish the necessary scienter for contributory liability even if the

product or service being supplied is capable of noninfringing uses. For example, in perhaps the first contributory copyright infringement case, Harper v.

Shoppell, the defendant was held liable for selling a

printing plate that he knew would be used for infringement, 28 F. 613, 615 (C.C.S.D.N.Y. 1886), despite the fact that the plate was susceptible of noninfringing uses, see Harper v. Shoppell, 26 F. 519, 521

(C.C.S.D.N.Y. 1886). It was the same in early patent

cases, prior to the adoption of 35 U.S.C. § 271(c) in

1952. In Bowker v. Dows, 3 F. Cas. 1070 (C.C.D. Mass.

1878) (No. 1,734), the defendant was held liable for

selling saponin extract “to persons who intend to use

it in the combination claimed in the patent,” even

though selling the extract without such knowledge

would not have been an infringement. Id. at 1071. In

Thomson-Houston Elec. Co. v. Ohio Brass Co, 80 F.

712 (6th Cir. 1897), then-Judge Taft similarly observed that where component parts are “adapted to

other uses than in the patented combination” contributory infringement could still be proven by

“affirmatively” establishing “the intention to assist in

infringement,” rather than by inferring it from infringing use. Id. at 723.

Notice of specific infringing acts can provide the

requisite knowledge, but the mere fact of receiving

such a notice from an alleged rightsholder is not by

itself sufficient. The circumstances of the notice are

important. A detailed notice from “an established and

well-known copyright owner and/or representative”

may be sufficient, see 4 Nimmer § 13E.03[B][3][b],

whereas a notice from an unknown entity or a subscriber’s competitor may not. In this case, an online

anti-piracy firm hired by dozens of the largest recording companies and music publishers sent detailed notices providing information concerning particular infringing sound recording files being distributed by

specific Cox subscribers at precise dates and times.

Pet. App. 167a. The district court found the notices

sufficient to establish “knowledge of specific conduct

which allegedly infringed all sound recordings and

musical compositions identified in suit” and granted

summary judgement on the knowledge element. Pet.

App. 172a. Indeed, if the notices here were not sufficient, it is difficult to imagine what notices would be.

III. The Requirement of “Material Contribution”

in Copyright Law Is Coextensive with “Substantial Assistance” in Tort Law

While the majority of lower courts have followed

parallel courses in copyright law and civil aiding and

abetting law on the required state of mind, finding

knowledge or reason to know of the tortfeasor’s plan

to be sufficient, that has not been the case for the

amount of assistance. For “material contribution,”

a “direct connection” to the infringement is needed,

and if so why payment processors, utility companies,

or hardware manufacturers do not have it. See Perfect

10, Inc. v. Visa Int’l Serv. Ass’n, 494 F.3d 788, 796, 800

(9th Cir. 2007). Other courts have suggested that

providing the “sites and facilities” for infringement is

sufficient, Fonovisa, Inc. v. Cherry Auction, Inc., 76

F.3d 259 (9th Cir. 1996), in which case any online service materially contributes to infringing activity on its

site or network, see 4 Nimmer on Copyright

§ 13E.03[B][2][b][iii] (citing cases). Still others have

found material contribution when the defendant’s

product or service is “the sole instrumentality” or “indispensable” for the infringement. Capitol Records,

Inc. v. MP3tunes, LLC, 821 F. Supp. 2d 627, 648

(S.D.N.Y. 2011); Pet. App. 26a.

Civil aiding and abetting cases, on the other hand,

have developed a rich set of factors for decisionmakers

to consider in lieu of a bright-line test. First set out in

the Restatement (First) of Torts § 876 cmt. b (A.L.I.

1939), and explicated further in the canonical case of

Halberstam v. Welch, 705 F.2d 472 (D.C. Cir. 1983),

and this Court’s decision in Twitter, Inc. v. Taamneh,

598 U.S. 471 (2023), the factors call for courts or juries

to consider “the nature of the act encouraged; the

amount [and kind] of assistance given; the defendant’s

absence or presence at the time of the tort; his relation

to the tortious actor; … the defendant’s state of mind;

[and the] duration of the assistance provided.” Halberstam, 705 F.2d at 483-84; Restatement (Second) of

Torts § 876 cmt. d (A.L.I. 1979). This inquiry is not an

atomized “sequence of disparate, unrelated considerations,” but rather one intended to resolve the ultimate

issue as to whether the defendant’s “participation in

another’s wrongdoing … is both significant and culpable enough to justify attributing the principal wrongdoing to the aider and abettor.” Twitter, 598 U.S. at

504; Restatement (Third) of Torts: Inten. Torts to Persons § 10 reporters’ note cmt. d (A.L.I., Tentative Draft

No. 3, 2018). The outcome of that inquiry must be further balanced against the defendant’s scienter: the

greater the defendant’s knowledge, the more significant smaller acts of assistance become, and vice versa.

Twitter, 598 U.S. at 491; Restatement (Third) of Torts:

Liab. for Econ. Harm § 28 cmt. d (A.L.I. 2020) (“[A]

clear understanding of wrongdoing can make a small

act of assistance more blameworthy”).

It is this sort of nuanced inquiry that can distinguish cases in which a person’s assistance, although

in some sense necessary to the outcome, is nevertheless insubstantial, from cases in which even small or

routine acts of assistance produce liability. An employee who is directed to deliver a message to co-workers ordering the commission of a tort provides insubstantial assistance to the tortious act, primarily

because of the employee’s relationship to the tortious

actor: a subservient one, with no authority to countermand the order. See Restatement (Second) of Torts §

876 cmt. d illus. 9; Restatement (Third) of Torts: Inten. Torts to Persons § 10 cmt. d illus. 15. The amount

and kind of the assistance is also slight, namely mere

delivery of a message; and the duration of the assistance is short, a single act.

By contrast, a person who hands an ordinary tool

that would be useful in opening an ATM machine to a

friend known to be planning a burglary is providing

substantial assistance, even though lending tools to

friends is usually perfectly innocent. See United States

v. Thompson, 539 F. App’x 778, 779 (9th Cir. 2013). So

too a broker who routinely processes trades from an

investment advisor that the broker knows to be churning, thus earning the broker extra commissions, is

substantially assisting the churning, Restatement

(Third) of Torts: Liab. for Econ. Harm § 28 cmt. d illus.

6, even though providing routine financial services is

typically free from liability, see Mendelsohn v. Cap.

Underwriters, Inc., 490 F. Supp. 1069, 1083–84 (N.D.

Cal. 1979).

It is thus incorrect to argue, as Cox and others appear to, that providing general-use communications

services to the public can never substantially assist a

tort. See Pet. Br. 28. “Routine” and “normal everyday

business practices” might require “a higher degree of

knowledge” to constitute substantial assistance than

shady or unusual business practices, but once that

knowledge is achieved, liability will attach to any further aid. Camp v. Dema, 948 F.2d 455, 459 (8th Cir.

1991); see also Casey v. U.S. Bank N.A., 127 Cal. App.

4th 1138, 1145 (2005) (“[C]ommon sense tells us that

even ‘ordinary business transactions’” may be substantial assistance “if the bank actually knew those

transactions were assisting the customer in committing a specific tort.”).

It is therefore true both that Cox can be held contributorily liable for knowingly providing substantial

assistance to infringing users, and that mere delivery

of communications will not suffice for aiding and abetting liability. Providing an undifferentiated service to

unknown wrongdoers fails both the knowledge and

the substantial assistance requirements. For example, in Twitter, the plaintiffs did not even allege that

any ISIS member ever used the defendants’ platform

to plan the attack that killed their family member.

Twitter, 598 U.S. at 498. Without any actual communications connected to the attack, the platforms could

not have known of them, nor could their services have

substantially assisted the attack.

Instead, the claim in Twitter was that the platforms

were liable for failing to find and remove terrorist

groups that might be using their services for other

things. Id. at 481-82. In other words, the plaintiffs

were claiming liability for providing any services to

someone who is known to be committing a crime or

tort, regardless of whether the services are at all connected to the wrongdoing. Aiding and abetting liability does not stretch that far. See Restatement (Third)

of Torts: Liab. for Econ. Harm § 28 cmt. d illus. 3 (no

liability for drafting lease for buyer known to be defrauding an employee).

Nor did aiding and abetting liability reach the complaint in Smith & Wesson Brands, Inc. v. Estados

Unidos Mexicanos, 605 U.S. 280 (2025). There, Mexico’s complaint alleged only that “some, though unidentified, dealers” in the defendant’s arms “often engage in illegal transactions with Mexican traffickers.”

Id. at 296. But without knowledge of which dealers

were engaging in illegal transactions, Smith & Wesson’s sales of identical firearms to a broad array of distributors could not amount to aiding and abetting illegal transactions. Id. at 297-98.

Where the defendant has more specific knowledge,

however, and provides more targeted assistance, aiding and abetting liability can arise. In Direct Sales Co.

v. United States, 319 U.S. 703 (1943), a criminal conspiracy case, a drug manufacturer and distributor

made it easy for physicians to order large quantities

of narcotics. It sold them in large lots of 500 to 5,000

tablets, offered discounts on large volume sales, and

suggested re-orders. Id. at 706-07. It continued these

practices even after being warned by the Bureau of

Narcotics that orders of more than 400 tablets per

year were likely illegitimate. Id. at 707. This Court

held that Direct Sales’s “high-pressure” sales tactics

for a controlled substance that resulted in a particular

doctor ordering thousands of tablets amounted to a

conspiracy to violate narcotics laws. Id. at 712-13. The

volume of tablets the doctor was purchasing were essentially good for nothing but illegal sales.

The same logic applies to contributory infringement. Knowledge that some unidentified purchasers

of a product will use it to infringe is insufficient to

make sale of that product “material contribution” to

their infringement, unless the product can only be

used for infringement. See Sony Corp. of Am. v. Universal City Studios, Inc., 464 U.S. 417, 442 (1984). But

assisting a particular known infringer may rise to the

level of material contribution. Whether it does will involve a balancing of circumstances captured in the

Halberstam factors.

Under that inquiry, the entities that troubled the

Ninth Circuit—power companies, hardware manufacturers, and payment processors—will likely fall short

of material contribution. See Perfect 10, Inc. v. Visa

Int’l Serv. Ass’n, 494 F.3d 788, 800 (9th Cir. 2007).

Companies outside the content and communication industries are less able to assess the reliability and authority of the notices that they receive. Their connection to the infringing activity is remote. The goods and

services they provide have enormous value, but their

relationship with customers allows for little in the way

of graduated response to infringement.

Providers within the content and communications

industries, on the other hand, such as search engines,

web hosts, and telecommunications services, are more

likely to provide material contribution to infringement. They are more likely to have encountered wellknown content companies or investigatory organizations. They are protected from copyright infringement

liability by statutory immunities, provided they comply with preconditions requiring repeat infringer policies and responses to takedown notices. See 17 U.S.C.

§ 512. The assistance they provide directly impacts

the copying and public distribution of copyrighted

works, and their relation to the tortious actor may allow more targeted responses, such as removing material or slowing connections.

Cox and others argue that aiding and abetting liability, and therefore contributory infringement liability, cannot possibly attach to failures to take action

against infringers. See Pet. Br. 32. But continuing to

supply goods or services after gaining knowledge is an

act of assistance, not an omission of ceasing to assist.

It is substantial assistance to continue processing

churning trades. See Armstrong v. McAlpin, 699 F.2d

79, 91 (2d Cir. 1983). It is substantial assistance to

provide morphine to a physician after having been

warned by the Bureau of Narcotics. See Direct Sales,

319 U.S. at 707. It is substantial assistance to continue handing erasers to negligent students in an

eraser fight. See Keel v. Hainline, 331 P.2d 397 (Okla.

1958). It is substantial assistance to keep supplying

goods to a person one knows will use them for

trademark infringement, Inwood Labs., Inc. v. Ives

Labs., Inc., 456 U.S. 844, 854–55 (1982), even if one is

operating under a contract for such goods. And it can

be substantial assistance to keep supplying the same

level of online services to a user known to be engaging

in significant acts of copyright infringement. 4 Nimmer § 13E.03[B][2][b][iii].

IV. The Jury Was Presented with Ample Evidence to Conclude Cox Had Both Knowledge

and Provided Substantial Assistance

The courts below were too demanding concerning

the defendant’s mental state and vague in affirming

the jury’s verdict on material contribution. See Pet.

App. 21a, 26a. The jury itself, however, was clearly instructed, without objection on this ground from Cox,

that the plaintiffs had to prove the Gershwin test for

contributory liability: that “Cox knew of specific instances of infringement,” and that “Cox induced,

caused, or materially contributed to the infringing activity.” See Jury Instrs. at 25, Dkt. No. 671 (Instr. No.

24); Cox’s Revised Proposed Jury Instrs. at 31, Dkt.

No. 645 (Instr. No. 27). The jury received ample evidence and argument on each of these elements.

First, the parties litigated the issue of the basis of

Cox’s knowledge of infringement and the reliability of

the notices it received, even though summary judgement had been granted on the knowledge element. As

this Court has observed, the knowledge of the secondary actor and the nature of its assistance are closely

intertwined, making it difficult to consider one

without the other. See Twitter, Inc. v. Taamneh, 598

U.S. 471, 503-04 (2023); Restatement (Third) of Torts:

Liab. for Econ. Harm § 28 cmt. d (A.L.I. 2020). There

was considerable testimony by the plaintiffs’ and defendant’s experts concerning exactly what the notices

established and how reliable they were, and Cox argued to the jury that it was justified in staying its

hand as a result. See Tr. 2991:20–2992:8 (Cox testimony that in “most cases” subscriber was not person

infringing).

Second, there was also considerable testimony and

argument to jury that covered all six of the Halberstam factors. The jury instructions in this case did

not elaborate on the meaning of “material contribution,” but that is not unusual. Jury instructions in contributory infringement cases typically leave additional factors “for argument by counsel.” Federal Civil

Jury Instructions of the Seventh Circuit 12.62 at 343

(2017). Pattern jury instructions for civil aiding and

abetting similarly do not tend to define “substantial

assistance.” See, e.g., 2 Judicial Council of California

Civil Jury Instructions, CACI No. 3610 at 710 (2024).

For the “nature of the act encouraged,” the plaintiffs presented evidence of millions of instances of infringement, much of it at the hands of repeat infringers. Resp. Br. 12. Lengthy testimony focused on the

“amount and kind of assistance given,” such as what

Cox did to assist infringement, what it did to prevent

infringement, and the harm of suspension or

termination of service. Resp. Br. 15-17; Pet. Br. 10-12;

Tr. 3015:15–19 (Cox closing statement). The duration

of Cox’s alleged assistance was a period of two years.

In the online context, “the defendant’s absence or

presence at the time of the tort” cannot be taken literally. But in real-world environments, the defendant’s

presence at the scene of the tort gives the defendant

much more of an ability to appreciate the gravity and

imminence of the harm, and to take action to stop it.

Cox presented evidence to the jury that it was unable

to confirm whether its subscribers were infringing and

unable to block them from using BitTorrent. Pet. Br.

9; Tr. 1022:12–25 (Cox testimony on inability to

block). The plaintiffs presented evidence that Cox was

making numerous decisions to waive its repeat infringer policy for particular subscribers in order to

avoid ever terminating or suspending their accounts.

See Tr. 2962:4-23 (Plaintiffs’ closing statement). As for

Cox’s “relation to the tortious actor,” Cox is a large service provider with millions of subscribers, Pet. Br. 9;

the plaintiffs presented evidence that the most important part of that relationship was the subscription

fee, Resp. Br. 16.

Finally, both parties presented extensive evidence

concerning “the defendant’s state of mind.” The plaintiffs introduced emails showing a lack of concern for

team, but also a corresponding lack of hesitancy to terminate subscribers for failure to pay their bills. Resp.

Br. 15-16, 18. Cox produced testimony that it was

seeking to address the infringement problem through

education and avoiding the drastic step of cutting off

someone’s internet connection. Pet. Br. 10-11; Tr.

1021:21–1022:4, 1025:24–1026:7 (Cox testimony that

purpose of abuse group was education, with termination as last resort).

The jury thus heard evidence and argument pertaining to Cox’s knowledge of infringing activity and

whether, based on the Halberstam factors, it materially contributed to that activity. After hearing all of

the evidence and deliberating, the jury returned a verdict in favor of the plaintiffs. There is no legal infirmity in that verdict.

CONCLUSION

Cox was given a fair trial before a jury of its peers

that was properly instructed on the Gershwin test and

had all of the evidence it needed to decide whether Cox

knowingly and substantially assisted specific subscribers’ infringing acts. The jury determined that Cox

was liable. This Court should thus affirm the Fourth’s

Circuit’s decision below on contributory liability, taking the opportunity to clarify the test for such liability

in future cases.

Respectfully submitted,