Deque Systems Inc. v. Browserstack, Inc.

CourtCourt of Appeals for the Fourth Circuit
DecidedJune 5, 2026
Docket25-1534
StatusPublished

This text of Deque Systems Inc. v. Browserstack, Inc. (Deque Systems Inc. v. Browserstack, Inc.) is published on Counsel Stack Legal Research, covering Court of Appeals for the Fourth Circuit primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Deque Systems Inc. v. Browserstack, Inc., (4th Cir. 2026).

Opinion

USCA4 Appeal: 25-1534 Doc: 56 Filed: 06/05/2026 Pg: 1 of 26

PUBLISHED

UNITED STATES COURT OF APPEALS FOR THE FOURTH CIRCUIT

No. 25-1534

DEQUE SYSTEMS INC.,

Plaintiff – Appellant,

v.

BROWSERSTACK, INC.; BROWSERSTACK SOFTWARE PVT, LTD,

Defendants – Appellees,

and

BROWSERSTACK LIMITED,

Defendant.

Appeal from the United States District Court for the Eastern District of Virginia, at Alexandria. Anthony John Trenga, Senior District Judge. (1:24-cv-00217-AJT-WEF)

Argued: March 18, 2026 Decided: June 5, 2026

Before AGEE, Circuit Judge, and TRAXLER and FLOYD, Senior Circuit Judges.

Affirmed by published opinion. Judge Agee wrote the opinion, in which Senior Judge Traxler and Senior Judge Floyd joined.

ARGUED: Timothy Allen Diemer, JACOBS & DIEMER, P.C., Detroit, Michigan, for Appellant. Carolyn C. Chang, MARTON RIBERA SCHUMANN & CHANG LLP, San Francisco, California, for Appellees. ON BRIEF: Courtney E. Evans, JACOBS AND USCA4 Appeal: 25-1534 Doc: 56 Filed: 06/05/2026 Pg: 2 of 26

DIEMER, P.C., Detroit, Michigan; Stephen P. Dunn, Troy, Michigan, Justin P. Bagdady, BODMAN PLC, Ann Arbor, Michigan, for Appellant. Roman Lifson, Belinda D. Jones, CHRISTIAN & BARTON, LLP, Richmond, Virginia; Ryan J. Marton, MARTON RIBERA SCHUMANN & CHANG LLP, San Francisco, California, for Appellees.

2 USCA4 Appeal: 25-1534 Doc: 56 Filed: 06/05/2026 Pg: 3 of 26

AGEE, Circuit Judge:

Deque Systems Inc. (“Deque”) and BrowserStack, Inc. (“BrowserStack”) are

competing software companies in the accessibility testing market. Deque sued

BrowserStack, alleging that it was infringing Deque’s copyrighted materials. After Deque

repeatedly failed to disclose its damages calculations and evidence of the same, the district

court excluded evidence of Deque’s damages as a sanction under Federal Rule of Civil

Procedure 37(c)(1). In turn, the court granted summary judgment for BrowserStack on all

claims. Deque now appeals both decisions. Finding no error, we affirm the district court’s

judgment in full.

I.

A.

The salient facts are largely undisputed. Deque is a web accessibility software and

services company that develops and sells software to help businesses ensure their websites

are accessible to those with visual and hearing impairments. Two of its products are

relevant here: (1) a website testing program known as DevTools, and (2) a proprietary rules

engine (“Rules Help Pages”). Deque spent numerous years and considerable money

developing DevTools, which website developers can install as a browser extension to test

webpage accessibility. DevTools automatically flags accessibility issues and directs the

user to the Rules Help Pages, which then explain potential solutions. Deque registered

multiple versions of DevTools and the Rules Help Pages with the United States Copyright

Office.

3 USCA4 Appeal: 25-1534 Doc: 56 Filed: 06/05/2026 Pg: 4 of 26

A user can access a free version of DevTools or purchase a “Pro” version that

includes more features. To access either, a user must agree to Deque’s “Software License

Terms,” which prohibit the user from copying or replicating DevTool’s source code. See

J.A. 923 (providing that a user “may not, and may not allow any third party to: [d]ecompile,

disassemble, decrypt, or reverse engineer [DevTools] or attempt to derive the source code

for any part of [DevTools]; . . . [or] [m]odify or create derivative works of [DevTools]”);

see also J.A. 931–32. In addition, creating an account on Deque’s website—which a user

must do to access the Rules Help Pages—requires agreeing to Deque’s Terms of Use.

Those provide that “[t]he information on [Deque’s] website is protected by copyright.

Except as specifically permitted, no portion of this website may be distributed or

reproduced by any means, or in any form, without Deque’s prior written permission.” J.A.

939.

B.

BrowserStack sought to enter the accessibility testing market sometime in 2021.

Internal BrowserStack documents reflect that, initially, the company sought to either

acquire Deque or “build on top of” Deque’s products. J.A. 1738. Acting on that desire,

BrowserStack approached Deque about a potential acquisition, which never came to pass.

Instead, beginning in late 2021, more than 100 BrowserStack employees created accounts

to access DevTools—thereby agreeing to Deque’s Software License Terms and Terms of

Use. At least seven accounts had Pro licenses.

In 2022, BrowserStack rolled out its Accessibility Toolkit, which, like DevTools,

was available as a browser extension. After its launch, BrowserStack advertised the

4 USCA4 Appeal: 25-1534 Doc: 56 Filed: 06/05/2026 Pg: 5 of 26

Accessibility Toolkit on its website, including a side-by-side comparison to DevTools.

That comparison represented that the Accessibility Toolkit is “5x faster” than Deque’s

products and that Deque’s products lacked certain tools that were available with the

Accessibility Toolkit. J.A. 1237.

C.

1.

In February 2024, Deque sued BrowserStack, alleging infringement under the

Copyright Act, 17 U.S.C. § 501(a); false advertising under the Lanham Act, 15 U.S.C.

§ 1125, and Va. Code Ann § 18.2-216; breach of contract; and unjust enrichment. Deque’s

theory of liability was that BrowserStack violated the Software License Terms by reverse

engineering DevTools’ source code, which it then used to develop the Accessibility

Toolkit. In other words, that BrowserStack’s Accessibility Toolkit, i.e., the “Infringing

Software,” infringed Deque’s “Copyrighted Works,” which include sixteen versions of

DevTools released between 2018 and 2021. According to Deque, BrowserStack copied the

Rules Help Pages to create its own version of the same. Deque also alleged that

BrowserStack made false statements in the advertisements on its website.

In its complaint, Deque asked the court to: (1) enjoin BrowserStack from further

copyright infringement and false advertising; (2) order an audit of BrowserStack’s use of

DevTools; and (3) award Deque: (a) actual damages, (b) lost profits, (c) monetary relief

for the damage to its goodwill and reputation, (d) the disgorgement of BrowserStack’s

profits obtained from the copyright infringement, and (e) its attorney’s fees and costs.

5 USCA4 Appeal: 25-1534 Doc: 56 Filed: 06/05/2026 Pg: 6 of 26

2.

The district court entered a Rule 16(b) scheduling order that established deadlines

for the parties to exchange initial and expert disclosures (June 7 and August 9, 2024,

respectively) and set a discovery cut-off date (October 11, 2024). Discovery opened on

April 18, 2024. Deque purported to serve its Rule 26(a)(1) initial disclosures on the June 7

deadline but didn’t provide a “computation of each category of damages claimed” or

reference or include any documents or evidence to support its damages claim as required

by Fed. R. Civ. P. 26(a)(1)(A)(iii). 1

A couple of weeks later (June 21), BrowserStack served interrogatories, including

one that asked Deque to identify the categories and calculations of its claimed damages. In

its response submitted over a month later, Deque again failed to disclose that information,

Free access — add to your briefcase to read the full text and ask questions with AI

Related

Anderson v. Liberty Lobby, Inc.
477 U.S. 242 (Supreme Court, 1986)
Hoffman v. Construction Protective Services, Inc.
541 F.3d 1175 (Ninth Circuit, 2008)
Denise Wilkins v. Vicki Montgomery
751 F.3d 214 (Fourth Circuit, 2014)
Holland v. Big River Minerals Corp.
181 F.3d 597 (Fourth Circuit, 1999)
Saudi v. Northrop Grumman Corp.
427 F.3d 271 (Fourth Circuit, 2005)
Dietz v. Bouldin
579 U.S. 40 (Supreme Court, 2016)
Saul Benjamin v. Nicholas Sparks
986 F.3d 332 (Fourth Circuit, 2021)
Foodbuy, LLC v. Gregory Packaging, Inc.
987 F.3d 102 (Fourth Circuit, 2021)
Henry v. R. K. Chevrolet, Inc.
254 S.E.2d 66 (Supreme Court of Virginia, 1979)
United States v. Arthur Stover
131 F.4th 199 (Fourth Circuit, 2025)

Cite This Page — Counsel Stack

Bluebook (online)
Deque Systems Inc. v. Browserstack, Inc., Counsel Stack Legal Research, https://law.counselstack.com/opinion/deque-systems-inc-v-browserstack-inc-ca4-2026.