Judging Similarity

• Author: Shyamkrishna Balganesh & Irina D. Manta
• Position: Professor of Law, University of Pennsylvania Law School/Associate Professor of Law, Maurice A. Deane School of Law at Hofstra University
• Pages: 267-290

267

Judging Similarity

Shyamkrishna Balganesh, Irina D. Manta, & Tess Wilkinson-Ryan

ABSTRACT: Copyright law’s requirement of substantial similarity requires

a court to satisfy itself that a defendant’s copying, even when shown to exist

as a factual matter, is quantitatively and qualitatively enough to render it

actionable as infringement. By the time a jury reaches the question of

substantial similarity, however, the court has usually heard and analyzed a

good deal of evidence about: the plaintiff, the defendant, the creativity

involved, the process through which the work was created, the reasons for

which the work was produced, the defendant’s own creative efforts and

behavior, and, on occasion, the market effects of the defendant’s copying.

Despite having this large body of evidence before it, the jury is required to

answer the question of substantial similarity through a mere comparison of

the two works. In this Essay, we report results from a series of experiments in

which subjects were presented with a pair of images and asked to assess the

similarity between the two works using the criteria ordinarily given to fact-

finders for the substantial similarity determination. When provided with

additional information about the simple fact of copying, or about the amount

of creative effort that went into the protected work, we saw an appreciable

variation (i.e., upwards) in subjects’ assessments of similarity between the

works, suggesting that fact-finders are sensitive to additional information

about the two works and the creators who produced them, contrary to what

current law assumes. Our study suggests that the availability and salience of

such additional information actively distorts fact-finders’ assessments of the

similarity between the two works, calling into question the purported

objectivity of the substantial similarity requirement as a whole.

 Professor of Law, University of Pennsylvania Law School.

 Associate Professor of Law, Maurice A. Deane School of Law at Hofstra University.

 Assistant Professor of Law and Psychology, University of Pennsylvania Law School.

Many thanks to Kristin Firth, Penn Law Class of 2016, for her outstanding research assistance.

We would also like to thank Chris Buccafusco, Jonah Gelbach, Gideon Parchomovsky, Dotan

Oliar, and participants at the 2014 Annual Conference of the American Law & Economics

Association (“ALEA”) at the University of Chicago and the 2014 Intellectual Property Scholars

Conference (“IPSC”) at the University of California–Berkeley School of Law for t heir helpful

comments and suggestions.

268 IOWA LAW REVIEW [Vol. 100:267

INTRODUCTION ............................................................................. 268

I. SUBSTANTIAL SIMILARITY: THEORY AND PRACTICE ....................... 272

A. THE TEST ............................................................................... 272

B. THE PROBLEM ........................................................................ 275

II. EXPERIMENTAL METHODS AND RESULTS ...................................... 278

A. STUDY 1 ................................................................................. 279

1. Methods ......................................................................... 279

2. Results ............................................................................ 280

B. STUDY 2 ................................................................................. 282

1. Methods ......................................................................... 282

2. Results ............................................................................ 283

III. DISCUSSION ................................................................................... 284

A. PSYCHOLOGICAL MECHANISMS FOR DISTORTED SIMILARITY

JUDGMENTS ............................................................................. 285

B. LABOR AND FREE-RIDING AS DISTORTIONARY INTUITIONS .......... 287

CONCLUSION ................................................................................ 288

INTRODUCTION

Fair use is commonly described as copyright law’s “most troublesome”

doctrine, in large part due to its open-endedness and uncertainty.1 In

practice, though, the complexities of the fair use doctrine pale in comparison

to what is central to almost all cases of copyright infringement: the question

of “substantial similarity.”2 Premised on the idea that “[n]ot all copying . . . is

copyright infringement,”3 copyright law’s substantial similarity doctrine

requires a plaintiff to satisfy a court that a defendant’s copying is quantitatively

and qualitatively enough like the original to render it actionable as

infringement. The defendant’s copying, in other words, needs to result in a

copy that is “substantially similar” to the plaintiff’s protected work for the

copying to be actionable.

Determining whether two things are alike may seem like a simple task,

but the substantial similarity requirement has been besieged by a host of

problems, most of which derive from the reality that current copyright

1. See Dellar v. Samuel Goldwyn, Inc., 104 F.2d 661, 662 (2d Cir. 1939).

2. See generally Mark A. Lemley, Our Bizarre System for Proving Copyright Infringement, 57 J.

COPYRIGHT SOC’Y U.S.A. 719, 719 (2010) (noting how it lies at the heart of copyright

infringement, and yet that there exist “surprising differences” in the working of the doctrine).

3. Feist Publ’ns, Inc. v. Rural Tel. Serv. Co., Inc., 499 U.S. 340, 361 (1991).