Kathryn KimballMizelle (Kat)


Washington + 1.202.879.3611 Miami + 1.305.714.9700

Kat Mizelle focuses on appeals and complex civil and criminal litigation. As a former federal prosecutor, she has significant argument experience in federal district court and has secured guilty verdicts in jury trials in state court. She has also filed briefs in the Fifth, Sixth, and D.C. Circuits and advised on numerous appeals on behalf of the federal government.

Prior to joining Jones Day, Kat served in the Tax Division at the Department of Justice (DOJ), where she prosecuted white collar offenses and led grand jury investigations of multimillion dollar tax shelters and fraudulent schemes. She also was a Special Assistant U.S. Attorney in the Eastern District of Virginia, where she prosecuted the largest human trafficking case in that district's history.

In addition, Kat served as counsel to the Associate Attorney General. In that role, she oversaw the Tax Division, advised on appeals and trials, developed DOJ-wide regulatory reform policy, led DOJ's efforts to defend free speech on college campuses, and testified before the Administrative Conference of the United States.

Kat has served as a law clerk at every level of the federal judiciary, including for Justice Clarence Thomas of the United States Supreme Court. Kat also serves as an adjunct professor at the University of Florida (UF). In January 2020, she co-taught the course "Religion Clauses of the First Amendment" with Justice Thomas at UF.


  • U.S. Chamber of Commerce files amici curiae brief in OSHA mandamus caseJones Day filed an amici curiae brief on behalf of the United States Chamber of Commerce and other trade associations opposing a mandamus petition which sought to order OSHA to adopt an emergency temporary standard during the COVID-19 pandemic.
  • Speaking Engagements

    Speaking Engagements Prior to Jones Day

    October 17, 2019
    The Role of the Supreme Court in the U.S. Federal System, The Honourable Society of the Middle Temple

    September 27, 2019
    In Pursuit of Truth: How the Framers Protected Liberty in the First Amendment, Constitution Day Lecture
    Geneva College

    September 23, 2019
    Career in Public Service, Congressional Classroom Speaker
    Randy Roberts Foundation

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