Katharine (Kate) O’Connor focuses her practice on complex antitrust litigation, antitrust investigations brought by the US antitrust regulators and state attorneys general, and counseling clients on antitrust compliance questions. Kate also regularly represents clients before the antitrust regulators related to mergers and acquisitions. Kate has experience representing clients in a wide array of industries, including healthcare, manufacturing, food and finance.

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  • Obtained highly favorable settlement on behalf of large physician practice organization in multiple disputes arising out of payor agreements
  • Obtained summary judgment defeating claims of monopolization, tying and exclusive dealing brought by an ambulatory surgery center against Southern Illinois Healthcare, a health system headquartered in Carbondale, Illinois
  • Counseled several healthcare providers and other healthcare industry participants on antitrust issues arising out of affiliations, joint ventures, competitor collaborations, and mergers and acquisitions across the country, as well as questions surrounding provider and payor contracting

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  • Benchmark Litigation, Future Star 2021 and 2022; 40 & Under Hot List 2019 and 2020
  • The Legal 500 United States, Next Generation Partner, 2020 and 2021
  • Super Lawyers Illinois Rising Star in Antitrust Litigation 2018 and 2019


  • American Health Lawyers Association


University of Illinois College of Law, JD, summa cum laude, Order of the Coif, 2010
University of Chicago, BA, with honors, 2001


US Court of Appeals for the Seventh Circuit
US District Court for the Central District of Illinois
US District Court for the Northern District of Illinois
US District Court for the Southern District of Illinois
US District Court for the Western District of Michigan
US District Court for the Eastern District of Wisconsin
US District Court for the Southern District of Indiana


Katharine O’Connor

Insights & Events / Media

Chicago, Illinois / McDermott Event / September 24, 2019

Today's General Counsel / June 13, 2017