Wainstein worked for the
Federal Bureau of Investigation, as General Counsel and as Chief of Staff to the FBI Director. Wainstein was appointed
homeland security advisor by President
George W. Bush on March 30, 2008. He was also assistant to the president for homeland security and counterterrorism and chaired the
Homeland Security Council. He was appointed as the "national continuity coordinator" under the auspices of
National Security Presidential Directive 51. After leaving the Bush administration, Wainstein joined the law firm of
O'Melveny & Myers. In 2012, he moved to
Cadwalader, Wickersham & Taft, where he was co-chair of the firm's litigation department and chair of the white-collar group. During his time at Cadwalader, Waintstein conducted an investigation which uncovered academic fraud and the
University of North Carolina at Chapel Hill. The 136-page report detailed a complex, multi-year scheme to inflate the grades of student athletes. From 2017 to 2020 Wainstein was a partner at the law firm of
Davis Polk & Wardwell LLP While at Davis Polk, Wainstein was reported to have represented clients including
AstraZeneca Pharmaceuticals LP;
Chevron Corp;
Comcast Corp;
JP Morgan Chase Bank NA;
Walmart Inc;
Purdue Pharma;
HSBC Holdings PLC;
Facebook Inc; and
General Dynamics Corp. On November 5, 2021,
President Joseph Biden nominated Wainstein for the position of
under secretary of homeland security for intelligence and analysis. The
United States Senate Select Committee on Intelligence held its open hearing on his nomination on January 12, 2022. The
United States Senate Committee on Homeland Security and Governmental Affairs held its hearing on his nomination on February 3, 2022. The full Senate voted to confirm Wainstein 63–35 on June 7, 2022. Wainstein joined
Mayer Brown in April 2025 to lead the law firm's global investigations and
white collar practice. == Personal life ==