Mark A. Flessner


Mark A. Flessner is a Chicago-based litigator and trial attorney with more than three decades of professional legal experience. He most recently served as Corporation Counsel for the City of Chicago, and previously as a partner at the firm Holland & Knight.

“I enjoy exercising: biking, walking, Peloton.”

Additional Details

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Full Bio

Mark has handled sophisticated litigation and regulatory matters across numerous industry sectors, having represented clients in multiple industries, including healthcare, retail, manufacturing, insurance and finance. He also has experience in the broad range of issues confronted by cities and municipalities, and he anticipates bringing business in those areas. Mark has substantial experience investigating wrongdoing within the corporate world and is well-versed in all aspects of corporate internal investigations.

Area of Legal Concentration

Mark has extensive trial experience, which includes bringing more than 50 cases to verdict and arguing more than 40 cases on appeal, with a high rate of success. He has advised clients on litigation risk management and assisted clients facing government scrutiny for criminal, civil and regulatory matters. Additionally, Mark has represented clients facing complex commercial litigation, internal corporate investigations, grand jury inquiries and issues involving the Foreign Corrupt Practices Act (FCPA).

Mark has a track record of business development in the law firm setting. The depth of his connections in Chicago and the Midwest allows him to do outreach across a variety of sectors to General Counsels and other decision makers.

Prior to entering private practice, Mark was a federal prosecutor at the United States Attorney’s Office in Chicago for 12 years. He led major investigations involving sophisticated and complex financial fraud. His prosecutions included public corruption, bank fraud, insurance fraud, securities fraud, and white-collar crime generally. Mark also has investigated international money laundering, terrorism and cases involving national security.

Mark has a strong commitment to community service and was the pro bono partner for Holland & Knight’s Chicago office. He was a lead attorney on a death penalty habeas corpus petition in Alabama and on a high-profile immigration case in Chicago. He also served as a member of the Federal Defender Panel in the Northern District of Illinois, providing legal representation to the indigent.


  • J.D., DePaul University College of Law
  • M.Div., University of Notre Dame
  • B.A. (Political Science), University of Illinois at Urbana-Champaign, with distinction
Professional Memberships
  • Federal Bar Association of Chicago, Board of Directors
  • Chicago State Foundation, Former Membetr of Board of Directors
  • Chicago Police Accountability Task Force, January-April 2016 of Lawyers
  • Just the Beginning Foundation, Board Member
  • Economic Club of Chicago
  • National Immigrant Justice Center Human Rights Awards, Chair, 2010-2014
  • Leading Lawyers Network, Peer Recommended 2013 – 2021
  • Former Treasurer, Lightfoot for Chicago Campaign
  • Greater Chicago Food Depository Finance and Legal Community Fundraiser, former Chairman
  • Leadership Greater Chicago, Board Member, Fellow, 1995-1996
  • Chicago Council of Lawyers, former Board Member; former Ethics Committee Co-Chair
  • West Suburban Mass Transit District, Former Trustee
  • Appleseed Fund for Justice, Former Board Member