Before starting his own law practice, Don worked for a well-regarded corporate law firm, for a state attorney general, and as a judicial law clerk. He has seen first-hand how the law is made, how it is shaped by court decisions, and how it affects business clients.
Don began his legal career with a one-year clerkship at the Texas Supreme Court, which is Texas's highest court and focuses on civil (not criminal) cases. Law clerks help the Court evaluate which of the roughly one thousand petitions filed each year should be granted and help the Justices write their opinions.
His private practice began as a litigator for Wachtell, Lipton, Rosen & Katz, a prominent New York law firm. While at Wachtell, Don worked on a variety of high-stakes commercial disputes. The cases included contract law, insurance coverage, business torts, securities fraud, bankruptcy, antitrust law, and federal regulatory investigations. He was a member of the trial team in IBP, Inc. v. Tyson Foods, a landmark merger case in the Delaware Court of Chancery, and also worked on the property-insurance lawsuit filed to help rebuild the World Trade Center. He particularly enjoyed his work on cases involving internet domain names, trademark law, copyright, and sports law.
In 2003, Don returned to Texas to serve as an Assistant Solicitor General (ASG) in the Texas Office of the Attorney General. ASGs are members of the Solicitor General's division, which handles the State's most important appellate cases. Don's cases involved questions of constitutional law and how courts should interpret new statutes. He has argued before the Texas Supreme Court, the United States Court of Appeals for the Fifth Circuit, and other Texas appellate courts.
In 2007, Don started his own law practice based in Austin, Texas.