William W. Flachsbart

William W. Flachsbart is a Partner and Chair of the Intellectual Property Litigation Team at Dunlap Bennett & Ludwig, focusing his practice on a broad array of patent, trade secret, and trademark issues for both high-tech companies and individuals. His technical expertise spans complex electrical patents, chemical patents, biotechnology patents, app software patents, and specifically includes significant experience in cases involving computer, network, electronic, and emerging technologies.

Flachsbart demonstrates experience representing both plaintiffs and defendants in patent litigation, handling individual patent lawsuits, and coordinating large-scale licensing campaigns. While current tracked appearances show him as lead counsel for a plaintiff in one matter, his firm's and his profile indicate substantial defense experience and a track record of resolving multimillion-dollar claims for both sides. He was previously a founding member of Flachsbart & Greenspoon, LLC.

Among his notable engagements, Flachsbart was involved in Alpha Modus, Corp. v. Cooler Screens, a patent infringement dispute concerning digital display and connected retail commerce technology, which resolved with a dismissal with prejudice in August 2025. He also successfully appealed a finding of inequitable conduct in 1st Media v. Electronic Arts, et al. before the Federal Circuit, and was counsel of record for the respondent in the related Supreme Court petition. His practice also includes representing patent owners in inter partes review (IPR) and post-grant proceedings before the Patent Trial and Appeal Board (PTAB), where his firm has extensive experience challenging and defending patents.

Admitted to practice in Illinois and before numerous federal courts, including the U.S. Supreme Court and the U.S. Court of Appeals for the Federal Circuit, Flachsbart earned his J.D. from Loyola University Chicago School of Law in 1996. He also holds an M.S. in Mathematics from the University of Oregon and an S.B. in Mathematics with a concentration in Computer Science from the University of Chicago.