William D. Ellerman

William D. Ellerman is a trial lawyer at Cherry Johnson Siegmund James PLLC in Dallas, Texas, practicing in intellectual property, business law, local counsel and commercial litigation. His more than two decades in the courtroom encompass patent infringement battles and high-stakes commercial disputes, and his caseload spans both plaintiff and defense work across state and federal forums.

Having taken on complex patent litigation for clients, Mr. Ellerman has handled cases for public research institutions and universities to multinational corporations, fledgling startups and individual inventors. He has handled disputes touching video streaming, wireless communications, mobile devices, semiconductors and medical devices, among other technologies, and has secured multimillion-dollar jury verdicts and settlements by framing technical subjects in clear, persuasive terms for judges and juries.

Mr. Ellerman’s business litigation practice covers contract conflicts, allegations of fraud, breaches of fiduciary duty, trade secret matters, banking and securities disputes, oil and gas controversies, and First Amendment cases. His trial work often sits alongside appellate practice; he has briefed matters to the U.S. Supreme Court and argued in numerous federal and state appellate courts.

A graduate of Tulane University with honors, Mr. Ellerman earned his J.D. from Baylor University School of Law, graduating summa cum laude as the top student in his class. His law school record includes recognition as Baylor’s Outstanding Law Student, leadership on Baylor’s national mock trial and moot court teams, and editorial roles on the Baylor Law Review. He is licensed in Texas and admitted to practice in the U.S. District Courts for the Northern, Eastern and Western Districts of Texas, the U.S. Court of Appeals for the 5th Circuit, the Federal Circuit and the U.S. Supreme Court.

Peers and clients have noted Mr. Ellerman’s strategic approach to litigation — managing risk, streamlining technical issues for lay decision-makers and pursuing outcomes that align with clients’ broader business goals. His work has been recognized by inclusion in the National Law Journal’s Top 100 Verdicts (2021). He remains active in the Dallas Bar Association’s Business Litigation and Intellectual Property Sections.