Don Vieira is a leading practitioner in the areas of national security, foreign investment review and cybersecurity.


Since joining private practice, Mr. Vieira has represented numerous clients in reviews before the Committee on Foreign Investment in the United States (CFIUS) and assisted clients on related issues, including Defense Security Service matters, as well as investigations involving export controls and economic sanctions.

He regularly represents companies in matters related to cybersecurity, including incident response investigations into data breaches and network intrusions by both state and non-state actors, and he has advised cybersecurity companies on the laws governing network intrusions and defense.

He also has represented numerous corporations, boards of directors and individuals in investigations, both internal and governmental, involving export controls and sanctions laws, the Foreign Corrupt Practices Act, inspectors general and congressional inquiries.

Mr. Vieira has served in senior national security positions in both the executive and legislative branches of the federal government. At the Department of Justice (DOJ), he was chief of staff of the National Security Division (NSD) and counselor to the assistant attorney general for national security. In that role, he provided counsel to the DOJ’s senior leadership on issues related to cybersecurity, export controls and sanctions, counterterrorism, counterintelligence investigations, telecommunication and information technology, electronic surveillance and a variety of other intelligence matters.

He also supervised the DOJ’s Foreign Investment Review Staff, which is responsible for representing the Justice Department on CFIUS and related Exon/Florio activities, as well as the Federal Communication Commission’s Team Telecom process. In this role, Mr. Vieira supervised the department’s work on hundreds of CFIUS reviews. In addition, he managed the NSD’s legislative portfolio and served as the division’s primary liaison to Congress, working closely with that legislative body on policy issues.

Prior to his appointment as NSD’s chief of staff, Mr. Vieira served as deputy chief counsel to the House Permanent Select Committee on Intelligence (HPSCI) and staff director of HPSCI’s Subcommittee on Oversight and Investigations. At HPSCI, he led several classified committee investigations. He also has served as a federal prosecutor in the DOJ’s Counterespionage Section, where he participated in the successful prosecution of espionage cases as well as export and economic sanctions enforcement matters.

Mr. Vieira has received numerous awards and honors for his prosecutorial and national security work from the DOJ, the Federal Bureau of Investigation, the Central Intelligence Agency, the Director of National Intelligence, the Office of the National Counterintelligence Executive, the Naval Criminal Investigative Service, the Department of State and Congress. They include the Office of the Director of National Intelligence’s Award for Community Excellence and the 2011 Attorney General Award for Exceptional Service.

Mr. Vieira has been selected for inclusion in the International Trade: CFIUS Experts category of Chambers Global and Chambers USA, in which clients note that he “very much understands the process and has a very good practical feel for how to address problems.” He also has been selected for inclusion in Lawdragon 500 and repeatedly recognized as one of Washington, D.C.’s Top Lawyers by Washingtonian



  • J.D., Georgetown University Law Center (With Honors)
  • B.A., Political Science, Boston University (With Honors)


  • District of Columbia
  • New York


Member, ABA Cybersecurity Legal Task Force

Donald L. Vieira

Partner, CFIUS; National Security; Cybersecurity and Privacy; International Trade