About Sheldon T. Zenner

Drawing on over 40 years of combined experience as a federal prosecutor and defense attorney, Sheldon Zenner expertly navigates his clients through high-stakes matters, including government and internal investigations, regulatory proceedings, all phases of criminal matters and related civil litigation. Sheldon's diverse client base is made up of corporations, high-ranking executives and company owners across a wide range of settings, including financial services, health care, the public sector and entertainment. Importantly, his representation of clients goes beyond advising on purely legal issues; it encompasses practical business implications, operational issues, public scrutiny, reputational damage and other considerations relevant to corporate and individual clients with businesses or livelihoods on the line.

A former federal prosecutor's perspective

The foundation of Sheldon's white-collar defense practice is the more than seven years he served as an assistant US attorney in Chicago, prosecuting numerous high-profile criminal matters and supervising the work of junior line prosecutors. Having a successful prosecutorial background gives Sheldon critical insights into, and the ability to anticipate, the government's strategic decision-making. It also informs Sheldon's approach as a defense lawyer. Although never anything short of zealous, he favors a search for common ground and reasonableness, whenever possible, while ready to go to the mat at trial when necessary.

That defense style has proven effective even when the government has opted for dramatic action. In one matter of note, 100 federal agents were deployed to execute a massive search of a client company's headquarter offices, seizing millions of dollars of products and attempting to interview executives. Sheldon immediately showed up on the scene to help control the situation, calm the employees and negotiate with the government and to address the press, which had been alerted by law enforcement to the raid. He then engaged with federal prosecutors in a year-long effort to persuade them that the company had engaged in no criminal conduct. Ultimately, after numerous meetings with the prosecutors and the submission of a lengthy legal analysis, the government was persuaded to decline any prosecution and return all of the seized products without any charges being filed.

In a recent high-profile federal criminal case, Sheldon was brought on as counsel just before trial. Sheldon and the Katten team analyzed all the evidence, determined that his client had not committed the crimes for which he was indicted, and obtained a meeting with the trial prosecutors and their supervisors, who were persuaded to dismiss the Indictment just weeks before the trial was to commence.

Although it is a paramount goal of any potential criminal matter to avoid prosecution, Sheldon is equally prepared to, and equally skilled at, trying cases. Among other victories, he convinced the government to abandon the first federal criminal computer-hacking prosecution after his damaging cross-examination of the government's expert at trial.

Many of Sheldon’s matters involve alleged violations of public corruption, antitrust, securities, or anti-fraud laws. Given the international nature of his clients' businesses, his work takes him to many foreign jurisdictions, including China, Japan, Brazil and South Africa, as well as many European countries. In addition to advising on government inquiries, Sheldon also helps clients conduct internal investigations into suspected wrongdoing and respond when they have been victimized by white-collar crime. Sheldon also has an active high-end civil litigation practice on behalf of companies and individuals who find that the skills honed in the federal criminal courts can be equally effective in civil disputes.

The breadth and depth of Sheldon's experience provides his clients with great assurance and comfort that they have counsel on board who can assist them to meet whatever challenges they may be facing.

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"Sheldon is a very nuanced and methodical thinker." "Sheldon is the rare lawyer that can draw from decades of experience while still being completely relevant and in tune with how one reaches commercially reasonable solutions." "Sheldon is exceptionally reliable and communicative. He analyzes complex issues quickly, identifies the most strategically significant points, and articulates clear, actionable recommendations."

Chambers USA 2026
(Illinois, Litigation: White-Collar Crime & Government Investigations) survey response 

Practice Focus

  • White-collar defense
  • Public Corruption
  • Securities litigation
  • Antitrust litigation
  • Tax disputes
  • Internal investigations

News

Presentations and Events

Practices
Industries
Education
  • Northwestern University School of Law, JD
  • Northwestern University, BA
Bar Admissions
  • Illinois
Court Admissions
  • US Court of Appeals, Seventh Circuit
  • US District Court, Northern District of Illinois, Trial Bar
Professional & Community Involvement
  • American Bar Association
  • Chicago Inn of Court
  • Goodman Theatre Board of Trustees
  • Northwestern University, Adjunct Faculty
  • Northwestern University Student Funded Public Interest Fellowship
Recognitions
Recognized or listed in the following:
  • Benchmark Litigation
    Local Litigation Star, 2016–2018, 2022, 2025-2026
  • Best Lawyers in America
    Criminal Defense: White-Collar, 1997–2026
  • Chambers USA
    Litigation: White–Collar Crime & Government Investigations, 2009–2026
  • Federal Bar Association, Chicago Chapter
    Award for Excellence in Pro Bono and Public Interest Service, 2023
  • Leading Lawyers Network
    Top 250 Leading Business Lawyers in Illinois, 2014
  • Legal Assistance Foundation
    Champion for Justice Award, 2010
  • Student Funded Public Interest Fellowship Program (SFPIF), Northwestern University School of Law
    Northwestern Law Distinguished Alumni Award, April 2014
  • Super Lawyers
    Illinois, 2005–2024
  • The International Who's Who of Business Lawyers
  • The Legal 500 United States
    Recommended Attorney, 2017–2018, 2020–2022, 2024–2026
  • Thomson Reuters
    Stand-out Lawyer, 2024–2026
  • Who's Who in America
  • Who's Who in American Law
  • Who's Who in the Midwest
  • Who's Who in the World
Award Methodologies