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William G. Sullivan

Of Counsel
fax +1 312.517.7576

William “Bill” Sullivan is a trial lawyer who represents plaintiffs and defendants, including companies of all sizes and individuals. He guides individuals and businesses through corporate governance and compliance issues involving state and federal regulatory agencies.

With more than 35 years of experience trying cases in state and federal courts, Bill litigates contested hearings involving temporary restraining orders and preliminary injunctions. He represents clients in Foreign Corrupt Practices Act, False Claims Act and World Bank investigations and tries cases in the U.S. Tax Court with his colleagues that have resulted in the savings of hundreds of millions of dollars. Bill is guided by the philosophy that a client’s best interests are served by avoiding a lawsuit, not winning at trial. When a case can’t be settled, Bill knows how to win at trial, having obtained favorable verdicts in four cases in federal court in one year – and convincing juries to award punitive damages in three of them.

Prior to joining Clark Hill, Bill represented clients in the Supreme Court of Illinois, the Illinois Appellate Court and the United States Courts of Appeals for the 5th, 7th and 11th Circuits. Bill also served in the Office of the Illinois Attorney General as Chief of the General Law and Consumer Protection Divisions, and Chief of the Toxic Waste Strike Force. He supervised the Public Utilities and Anti-Trust Divisions. Since leaving the Illinois Attorney General’s Office he has been appointed by four successor attorneys general as a special assistant attorney general. He has litigated cases in the state and federal courts on behalf of the state of Illinois, including a class action in which he represented the Illinois Toll Highway Authority.

Author of the following statutes:

  • Travel Promotion Consumer Protection Act, 815 ILCS 420/1
  • Illinois Burial Rights Act, 820 ILCS 135/1
  • Aggravated Stalking Law, 720 ILCS 5/12-7.4


J.D., with Honors, Illinois Institute of Technology, Chicago, Illinois, 1978


Named a Leading Lawyer in Chicago by Leading Lawyers℠ (2015-2024)


Chicago Bar Association

American Bar Association

Marquette Bank, Chicago, Illinois: Chair Compliance and Regulatory Committee (2015-present), Director Asset/Liability Committee (1994-present), Member Trust Committee (Chair 2004-2009)

State Bar Licenses


Court Admissions

U.S. District Ct., N.D. of Illinois
U.S. District Ct., N.D. of Illinois Trial Bar
U.S. District Ct., C.D. of Illinois
U.S. Tax Court
U.S. Court of Appeals, 5th Circuit
U.S. Court of Appeals, 7th Circuit
U.S. Court of Appeals, 11th Circuit
U.S. Supreme Court