Deque Systems Inc. v. Browserstack, Inc.

Court of Appeals for the Fourth Circuit·Decided June 5, 2026·No. 25-1534·Published

Opinion

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

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.

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.

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

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.

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, stating instead that it “intend[ed] to seek all available damages” and that “the calculations of the amount of damages that it seeks to recover, and all facts and opinions supporting such amounts, are incomplete at this time[.]” J.A. 484–85. That is, Deque proffered it

1

Deque’s disclosure statement simply stated:

Plaintiff seeks its lost profits and/or Defendants’ revenue attributable to Defendants’ copyright infringement, false advertising and breach of contract.

Alternatively, Plaintiff seeks damages in the amount that Defendants’ have been unjustly enriched through their unlawful actions. Plaintiff further seeks enhanced damages, attorneys’ fees, and pre- and post-judgment interest to the extent permitted by law.

Plaintiff will make available to Defendants the documents upon which it bases its computation of losses under Fed. R. Civ. P. 34 as discovery proceeds, subject to all appropriate reservations, objections, privileges, protections, or immunities from disclosure.

J.A. 151.

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