Tom O’Brien

Practice Group Chair - Professional Liability Litigation (Firmwide) Partner

Tom O'Brien


P: +1.214.953.6934
F: +1.214.661.4934

Chair of the Firmwide Professional Liability Litigation Group, Tom O'Brien has a national securities, shareholder, professional liability and commercial litigation practice. He enjoys and thrives at representing companies and professionals in their most critical moments, such as when they face a major securities fraud case or a malpractice suit challenging their work. Two cases he has litigated have reached the Supreme Court of the United States, and one case he tried ended in a $7 billion judgment described by the District Court and the Fifth Circuit as a “once in a lifetime result.” In re ASARCO, LLC, 751 F.3d 291, 296 (5th Cir. 2014). Following graduation from law school with high honors and before joining Baker Botts, Mr. O'Brien served as a law clerk to the Honorable Kim McLane Wardlaw of the United States Court of Appeals for the Ninth Circuit.

Securities and Shareholder Litigation. Mr. O'Brien has represented public companies, their officers and directors and public accounting firms in litigation and investigations in Delaware, New York, Texas, and other jurisdictions related to securities, mergers and acquisitions, corporate control, shareholder demands, financial reporting, short-swing profits, and audits. For example, he defended one of the most closely-watched securities fraud class actions of all time, which made two trips to the Supreme Court of the United States and resulted in defendants having the right to rebut the presumption of reliance at class certification. See Halliburton Co. v. Erica P. John Fund, Inc., 134 S. Ct. 2398 (2014).

Professional Liability Litigation. Mr. O'Brien also has defended law, audit, tax, and advisory firms against professional liability claims. He has represented professional service firms against a variety of claims brought by clients and non-clients inside and outside of Texas. For example, he received a dismissal of a lawsuit alleging that an international law firm committed fraud and breached a contract in connection with an arbitration proceeding. The dismissal was affirmed by the court of appeals, and the Supreme Court of Texas denied the plaintiffs' petition for review. Patten v. Johnston, Case No. 14-0433, in the Supreme Court of the State of Texas.

Commercial Litigation. Mr. O'Brien has significant experience with other complex business-related disputes as well, including substantial experience with bankruptcy litigation. Last fall, he was lead trial counsel in a contested hearing over the total enterprise value of a worldwide provider of oilfield transportation and search and rescue services. Complimenting the Baker Botts team led by Mr. O’Brien, the Bankruptcy Court said: “[T]his is the most fun that I’ve had since I’ve been on the Bench. . . . [E]verybody advocated for their clients in an effort to be what a lawyer is supposed to be.” In re Bristow Group, Inc., Case No. 19-32713-H2-11, in the United States Bankruptcy Court for the Southern District of Texas. Mr. O’Brien also participated in a four-week trial in a fraudulent transfer and breach of fiduciary duty case that resulted in a $7 billion judgment described by the District Court and Fifth Circuit as a “once in a lifetime result.” In re ASARCO, LLC, 751 F.3d 291, 296 (5th Cir. 2014). He also tried the two-week confirmation hearing in a bankruptcy case characterized by the Bankruptcy Court as “probably the most successful Chapter 11 of any magnitude in the history of the [Bankruptcy] Code.” Id. at 298.