Deque Systems Inc. v. Browserstack, Inc.

── Deque Systems Inc. v. Browserstack, Inc. ── Court: Court of Appeals for the Fourth Circuit Date: June 05, 2026 Category: General 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 repl