Mary Kay McCalla Martire - McDermott Will & Emery


Mary Kay McCalla Martire focuses her practice on a wide variety state and local tax issues. She advises clients on matters related to sales tax, with an emphasis on the sale of digital products. In addition, she advises business clients on income tax apportionment and remote employee withholding obligations. Mary Kay counsels individual clients on residency and income sourcing questions, and frequently advises captives and their insureds on direct procurement tax issues. She also has experience with state and local utility and telecommunications tax matters.

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  • Won Appellate Court verdict affirming dismissal of qui tam claim for over $1 million in attorneys’ fees. State of Illinois ex. rel. Stephen B. Diamond P.C. v. SR/Ecom, Inc., 2018 IL App. (1st) 172612
  • Won bench trial verdict for taxpayer in qui tam suit alleging failure to collect and remit sales tax on shipping charges. State of Illinois ex. rel. Stephen B. Diamond, P.C. v. Treasury Wine Estates Americas Co., No. 14 L 7563 (Aug. 30, 2016)
  • Won two appellate court rulings affirming the dismissal of qui tam lawsuits (State ex rel. Beeler, Schad & Diamond, P.C. v. Burlington Coat Factory Warehouse corp., 369 Ill. App. 3d 567 (1st Dist. 2006); People ex rel. Schad Diamond & Sheddon, P.C. v. QVC, Inc., 2015 IL App (1st) 13299 (April 21, 2015)) and obtained circuit court orders dismissing several other qui tam cases

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  • Martindale-Hubbell, AV Preeminent
  • International Tax Review, World Tax, 2017 to 2023
  • Illinois Super Lawyer 2005, 2008 to 2011


  • Chicago Bar Association, State and Local Tax Committee, past chair
  • Chicago Lawyers Committee for Civil Rights Under Law, Inc., past chair, past board member
  • Chicago Volunteer Legal Services, board member
  • PING! (Provide Instruments for the Next Generation), past treasurer and past board member
  • Oak Park River Forest Women Leaders in Philanthropy, 2023 chair
  • Parents’ Instrumental Music Organization, past chair, past board member


University of Michigan Law School, JD, 1985
Michigan State University, BA, 1982


United States Supreme Court
US Court of Appeals for the Sixth Circuit
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 (trial bar)
US District Court for the Eastern District of Michigan
Illinois Supreme Court
Michigan Supreme Court