William Joseph O'Brien

William Joseph O'Brien is a highly experienced patent litigation attorney, serving as lead counsel and counsel in complex intellectual property disputes. Based at One LLP, his practice spans a wide array of technologies, including medical devices, consumer electronics, software, optics, aerospace, manufacturing equipment, diagnostics, chemicals, and business method patents. He is well-versed in patent, trademark, trade dress, copyright, trade secret, and idea submission cases.

O'Brien primarily represents plaintiffs in patent infringement actions, as evidenced by his three tracked appearances, all on the plaintiff side, two as lead counsel. His firm profile highlights significant plaintiff-side successes, including securing a multimillion-dollar jury verdict in a patent infringement case for a medical device company, which was affirmed on appeal and fully collected. He also served as lead counsel for a major telescope manufacturer in five patent cases, leading to the settlement of three cases against a key competitor that included favorable royalties, inventorship correction, and patent transfer. While predominantly plaintiff-focused, his experience also includes successful defense outcomes, such as obtaining a favorable claim construction and summary judgment of non-infringement for an optical disc manufacturer, and achieving an early Markman hearing and summary judgment for a computer component manufacturer.

His career includes partnerships at prominent firms such as Christie Parker & Hale, O'Melveny & Myers (where he co-chaired the Patent and Technology Litigation Practice Group), and Alschuler Grossman Stein & Kahan, before joining One LLP. A notable ongoing case is FaceTec, Inc. v. Jumio Corporation et al., where O'Brien represents the plaintiff, FaceTec, Inc.. In a significant development related to this litigation, the U.S. Patent Trial and Appeal Board (PTAB) recently upheld the patentability of all four challenged claims central to FaceTec's biometric liveness detection technology, bolstering FaceTec's position in the district court infringement lawsuits against Jumio and iProov.

O'Brien earned his Juris Doctor from the University of California, Berkeley, School of Law, and his Bachelor of Arts in Economics from the University of California, Davis, where he was elected to Phi Beta Kappa. He was admitted to the State Bar of California in 1981.