Jack O'Neill

Jack O’Neill: Leading Trial Lawyer with 45+ Years of Experience

Jack O’Neill is a highly respected and accomplished trial lawyer with over 45 years of experience handling complex, high-stakes litigation. Known for his strategic thinking, courtroom prowess, and unwavering commitment to his clients' success, Mr. O’Neill has consistently achieved exceptional results across a broad spectrum of legal matters, including those within the oil and gas industry, corporate disputes, and complex litigation.

Mr. O’Neill’s career is defined by a remarkable track record of success, evidenced by numerous significant victories and a deep understanding of the legal landscape. He has been repeatedly recognized for his expertise, earning numerous accolades including being named in Lawdragon’s 500 Leading Litigators in America, Lawdragon’s 500 Leading Lawyers in America, and the Lawdragon Hall of Fame, along with recognition from Best Attorney USA and *Thomson Reuters*. His commitment to excellence is further reinforced by his membership in the American Board of Trial Advocates and the International Association of Defense Counsel.

Practice Areas

• Appellate Practice
• Commercial Litigation
• Natural Resources Law
• Oil and Gas Law
• Arbitration

Mr. O’Neill’s expertise spans a diverse range of legal areas, enabling him to provide comprehensive legal counsel and representation to clients of all sizes. Key areas of his practice include:

• Complex Litigation: Mr. O’Neill has consistently excelled in leading complex litigation matters, skillfully navigating intricate legal issues and presenting compelling arguments to achieve favorable outcomes.
• Trial Advocacy: He is a highly skilled courtroom advocate, adept at preparing and presenting cases effectively, examining witnesses, and persuading juries.
• Appellate Law: Mr. O’Neill’s appellate experience is unparalleled, having successfully appealed decisions in numerous high-profile cases, securing reversals and favorable judgments for his clients.
• Oil and Gas Law: Leveraging decades of experience within the energy sector, he provides specialized legal counsel to companies involved in all aspects of the oil and gas industry, including acquisitions, disputes, and regulatory matters.

Notable Case Experience

Mr. O’Neill’s resume boasts a remarkable portfolio of notable cases, showcasing his strategic acumen and courtroom dominance. Some highlights include:

• UPR, Inc. v. Pennzoil (Takeover Attempt): Co-trial counsel for UPR, Inc., successfully defending against an attempted hostile takeover by Pennzoil, demonstrating sophisticated corporate litigation expertise.
• Mitchell Energy Corporation – $204 Million Judgment Reversal: Lead counsel for Mitchell Energy Corporation, successfully overturning a $204 million judgment through strategic appellate advocacy, ultimately securing a favorable judgment.
• Key 1-11 Gas Well Blowout: Lead trial counsel for plaintiffs in the landmark Key 1-11 gas well blowout case, a complex environmental litigation matter highlighting his ability to manage multifaceted cases.
• McKesson Corporation – Trademark Infringement: Successfully defended McKesson Corporation in a significant trademark infringement case, securing a unanimous jury verdict.
• Employment Discrimination Case – American Subsidiaries of Foreign Companies: Lead counsel in a groundbreaking case establishing that American subsidiaries of foreign companies are subject to U.S. fair employment laws, significantly impacting corporate legal strategy.

Education & Credentials

• Bar Admissions: Admitted to the Bar of the State of Texas
• Awards & Recognition: Recognized in Best Attorney USA since 2014, Recognized: Appellate Practice, Recognized: Commercial Litigation, Recognized: Natural Resources Law, Recognized: Oil and Gas Law, Practice Area: Arbitration, Best Lawyers in America, 2014-2026, Lawdragon 500 Leading Litigators in America, 2022-2026, Lawdragon 500 Leading Lawyers in America, 2024-2025, Lawdragon 500 Leading Energy Lawyers, 2025, Lawdragon Hall of Fame, 2025, Texas Super Lawyers, Thomson Reuters, 2003-2025, Recognized in Chambers USA among the leading Commercial Litigation attorneys, 2024-2025, Martindale-Hubbell®