Rob Barthelmess


Thank you for your interest. Before you communicate with one of our attorneys, please note: Any comments our attorneys share with you are general information and not legal advice. No attorney-client relationship will exist between you or your business and O’Melveny or any of its attorneys unless conflicts have been cleared, our management has given its approval, and an engagement letter has been signed. Meanwhile, you agree: we have no duty to advise you or provide you with legal assistance; you will not divulge any confidences or send any confidential or sensitive information to our attorneys (we are not in a position to keep it confidential and might be required to convey it to our clients); and, you may not use this contact to attempt to disqualify O’Melveny from representing other clients adverse to you or your business. By clicking "accept" you acknowledge receipt and agree to all of the terms of this paragraph and our Disclaimer.


Rob Barthelmess is a litigation associate in O’Melveny’s Los Angeles office, where he devotes much of his practice to complex civil litigation, appeals, and white collar defense and corporate investigations. Before returning to O’Melveny in 2019, Rob served as a law clerk to the Honorable Ryan D. Nelson in the United States Court of Appeals for the Ninth Circuit.

Rob graduated cum laude from the Georgetown University Law Center. While in law school, Rob worked as a law clerk at the United States Senate Committee on the Judiciary, Subcommittee on Antitrust, Competition Policy and Consumer Rights, the United States Securities & Exchange Commission’s Division of Enforcement, and the Santa Barbara County District Attorney’s Office.


Bar Admissions

  • California

Court Admissions

  • US District Court, Central District of California
  • US Court of Appeals, Ninth Circuit


  • Georgetown University, J.D.: cum laude; Dean’s List; Executive Notes Editor, Journal of National Security Law & Policy
  • University of California at Los Angeles, B.A., Philosophy

Professional Activities


  • Honorable Ryan D. Nelson, United States Court of Appeals for the Ninth Circuit


  • United States Senate Committee on the Judiciary, Subcommittee on Antitrust, Competition Policy and Consumer Rights
  • United States Securities & Exchange Commission, Division of Enforcement
  • Representing multinational companies and individuals in fraud litigation in California state and federal courts
  • Conducting internal investigations and representing clients in connection with Department of Justice and US Securities & Exchange Commission investigations
  • Representing large corporations on appeal and advising clients on appellate strategy
  • Defending an electric-vehicle and technology company in an Alien Tort Statute action
  • Counseling a national managed care organization in connection with government audits