Tacy Flint is a premier appellate litigator who has won victories for her clients in high-stakes cases at all levels of the judiciary, through an uncommonly insightful legal perspective combined with zealous advocacy and business acumen. 

Tacy advocates for her clients from complaint through appeal, leading teams writing critical motions and briefs, presenting compelling oral argument, and developing litigation strategy that best advances her client’s position at every stage of litigation. In the words of one of Tacy’s clients, “She’s the heavyweight legal thinker and strategist you call when you want the knockout punch, be it an early dispositive motion or a Supreme Court brief. Tacy has a unique ability to tell her client’s story. A brief or motion written by Tacy does not simply set out key cases and facts. It builds the narrative.”

Tacy is Chambers USA-ranked for Litigation: General Commercial – Illinois (2023–2024). Her strong advocacy has also earned her recognition as a “Litigation Star” by Benchmark Litigation (most recently in 2024), as a “Notable Woman in Law” by Crain’s Chicago Business (2024), as a Salute! Women in Law honoree by Chicago Daily Law Bulletin (2023), and as one of the “60 Most Influential Women Lawyers” in Chicago by Crain’s Chicago Business (2017).

Tacy’s practice spans a wide range of legal issues, including antitrust, contract disputes, consumer class actions, ERISA, federal preemption, securities laws, and the First Amendment. She has argued or briefed major appeals in courts around the country—including the U.S. Supreme Court and the Illinois Supreme Court—winning historic judgments for her clients. Her appellate successes include judgments vacating a US$600 million jury verdict, striking down an unlawful state tax law, and vacating a federal regulation nationwide. In trial courts, she has prevailed on dispositive motions in cases seeking billions of dollars in damages and injunctions posing an existential threat to her clients; secured evidentiary rulings to reduce her clients’ exposure; and won defense judgments by providing strategic counseling on jury instructions and legal issues at trial and in post-trial briefing. 

Outside her practice, Tacy is dedicated to her community and contributes to the firm in a variety of ways, most recently as co-chair of the SidleyWomen committee. Prior to joining Sidley, she served as a law clerk to Judge Richard Posner of the U.S. Court of Appeals for the Seventh Circuit and Justice Stephen Breyer of the U.S. Supreme Court.