Gregg Costa is co-chair of the firm’s Trials Practice Group. Gregg offers clients a unique perspective as a former federal trial and appellate judge. His broad experience—having handled complex civil and criminal matters, at trial and on appeal, as advocate and judge—allows him to offer invaluable skills and strategic insights for both trials and investigations.
Before joining Gibson Dunn, Gregg served for more than ten years as a federal trial and appellate judge. He served on the U.S. Court of Appeals for the Fifth Circuit from 2014 to 2022. After his nomination by President Obama, the Senate confirmed him by a vote of 97-0. No federal appellate judge nominated since has received more votes. Gregg earlier served as a district judge for the Southern District of Texas from 2012 to 2014. When appointed to the bench, he was the youngest-sitting federal judge at age 39. Gregg presided over thirty federal trials in four different venues (he continued handling district court matters while serving on the court of appeals). He wrote precedential opinions in almost every area of the law, including antitrust, intellectual property, class actions, international arbitration, securities fraud, bankruptcy, conflicts of law, labor and employment, oil and gas, False Claims Act, administrative law, constitutional law, and criminal law. In press accounts of his tenure, he was described as an “exceptionally gifted jurist” with a “towering intellect” who was “respected by all sides.” The Federal Judicial Center invited Gregg on multiple occasions to teach new federal district judges.
Since his return to private practice, Lawdragon has named Gregg one of 500 Leading Global Litigators and one of 500 Leading Lawyers in America and Best Lawyers in America® listed him in Commercial Litigation, White Collar Defense, and Appellate Law. Most recently, Gregg was recognized by Best Lawyers® as Lawyer of the Year 2025 in Criminal Defense: White-Collar. Gregg was also recently recognized by Benchmark Litigation as a “Litigation Star.” American Lawyer recognized Gregg for successfully representing a group of lenders in a bankruptcy court trial—closely watched in the financial world—that validated a liability management transaction.
Before taking the bench, Gregg was an Assistant United States Attorney in Houston. In that role, he served as a lead prosecutor of Allen Stanford, the head of Stanford Financial Group, for orchestrating a multibillion-dollar international fraud scheme. Gregg is featured in a documentary about the case, The Man Who Bought Cricket. For his work on the Stanford case, Gregg received DOJ’s John Marshall Award for Trial of Litigation and the Assistant Attorney General’s Award for Exceptional Service. He also prosecuted cases involving kickbacks in the energy industry, public corruption, the Foreign Corrupt Practices Act, securities fraud, internet fraud, and counterfeit technology products. During his time as a federal prosecutor, Gregg served as a Deputy International Affairs Coordinator, during which he assisted with investigations in more than a dozen countries.
Gregg received his undergraduate degree from Dartmouth College in Government and Economics. He graduated with highest honors from the University of Texas School of Law, where he served as Editor-in-Chief of the Texas Law Review. After law school, he clerked for Chief Justice William Rehnquist and for Judge A. Raymond Randolph of the United States Court of Appeals for the D.C. Circuit. Between clerkships, he served as a Bristow Fellow in the Office of Solicitor General.
Before law school, Gregg taught elementary school in the Mississippi Delta through Teach for America. Gregg has remained involved in education, launching a nonprofit in Mississippi; serving on the boards of Teach for America’s Houston region and the Houston Urban Debate League; and helping teach Government at a Houston-area charter school. Gregg is also active in a number of organizations aiming to improve the justice system. He is a trustee of the Center for American and International Law and a member of the American Law Institute. Gregg also maintains an active pro bono practice and serves on Gibson Dunn’s Pro Bono Committee.
Capabilities
- Litigation
- Antitrust and Competition
- Appellate and Constitutional Law
- Class Actions
- Crisis Management
- Energy Regulation and Litigation
- Energy and Infrastructure
- Intellectual Property
- International Arbitration
- Securities Litigation
- Trials
- White Collar Defense and Investigations
Credentials
Education:
- University of Texas - 1999 Juris Doctor
- Dartmouth College - 1994 Bachelor of Arts
Admissions:
- Texas Bar
Clerkships:
- US Supreme Court, Hon. William Rehnquist, 2001 - 2002
- US Court of Appeals, DC Circuit, Hon. Raymond Randolph, 2000 - 2001