Tacy F. Flint

TACY FLINT is a co-leader of Sidley’s Supreme Court, Appellate, and Litigation Strategies practice. She is a premier appellate litigator who has won victories in high-stakes cases at all levels of the judiciary, advocating for her clients from complaint through appeal. 

Tacy’s strong advocacy has garnered extensive recognition. She is ranked in Band 1 by Chambers USA for Litigation: Appellate — Illinois (2024–2025). She has twice been named “Litigator of the Week” by the AmLaw Litigation Daily (2020, 2024) in recognition of nationally significant victories, and designated a runner-up five additional times. She has also been recognized as a “Litigation Star” by Benchmark Litigation (2025), 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). In 2025, Tacy was elected to the American Academy of Appellate Lawyers. 

“Tacy is extremely pragmatic and creative. She finds the way to win.”
Chambers USA 2025

Tacy is a superlative writer, having won cases with critical motions and briefs at all stages of litigation. She is equally renowned for her oral argument skills. She has argued in the U.S. Supreme Court, the Illinois Supreme Court, and federal and state courts of appeals across the country. Repeatedly, Tacy has won historic rulings for her clients — including vacatur of large jury verdicts, dispositive rulings in cases seeking billions of dollars in damages, and case-critical rulings on evidentiary and other legal issues.

 

“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.”
Chicago Daily Law Bulletin’s “40 Under Forty” 2017

 

As a two-time lymphoma survivor who recently celebrated her 20th “cancerversary,” Tacy is a devoted fundraiser for cancer research, including through the Leukemia and Lymphoma Society and Cycle for Survival. Tacy’s experience as a cancer survivor and commitment to fighting cancer has been included in Bloomberg, Chicago Lawyer, the Chicago Daily Law Bulletin, and the University of Chicago Law School Record.

Tacy also serves as a trustee of the Adler Planetarium, chairs the Board of Trustees of the NALP Foundation for Law Career Research and Education, and is a trustee of Impact for Equity. She was a 2021 Signature Fellow of Leadership Greater Chicago.
 
Tacy graduated first in her class with highest honors from the University of Chicago Law School. She served as a law clerk to Justice Stephen Breyer of the U.S. Supreme Court and Judge Richard Posner of the U.S. Court of Appeals for the Seventh Circuit.

Representative cases have included:

• In a 2025 argument before the U.S. Supreme Court, Tacy won a unanimous ruling that combat-disabled veterans are entitled to payment of Combat-Related Special Compensation without regard to when they applied for the benefit. Tacy delivered the oral argument, and was profiled in Bloomberg Law for her work on the case. 
• In the Supreme Court of Delaware, Tacy and team won a major precedential ruling for client Cantor Fitzgerald. Reversing a Chancery decision, the state’s high court rejected a challenge to the enforceability of a forfeiture-for-competition provision in Cantor Fitzgerald’s limited partnership agreement. 
• Tacy and team won dismissal of a putative class action filed in federal district court in Delaware, contending that the Cantor Fitzgerald limited partnership agreement violated federal antitrust laws. The AmLaw Litigation Daily awarded Tacy and her colleagues Litigator of the Week honors for this victory, noting that the team had “secured a key reversal from the Delaware Supreme Court” as well as this “follow-on antitrust litigation filed in federal court.”
• Arguing in front of the Seventh Circuit, Tacy won a sweeping victory for the Barack Obama Foundation against long-running efforts to block development of the Obama Presidential Center in Jackson Park on Chicago’s South Side. 
• For GOLO, LLC, Tacy won a judgment dismissing a putative class action filed in the U.S. District Court for the Eastern District of California, alleging that GOLO’s labeling violated state law. Sidley was retained after the client’s motion to dismiss, with different representation, was denied. Tacy recently argued for affirmance of the judgment in the Ninth Circuit.
• In the Third Circuit, Tacy authored the briefs and delivered oral argument on behalf of nine pharmaceutical manufacturers in a case of first impression concerning the knowledge requirement for False Claims Act cases. Tacy won affirmance of the dismissal of claims against her clients.
• In the Sixth Circuit, Tacy won a historic judgment on behalf of a class of Detroit schoolchildren, who contended that the State of Michigan violated their constitutional rights by compelling them to attend public schools without providing them a meaningful education that offered access to literacy. Although the district court had dismissed the claim, the Sixth Circuit reversed, holding that the Constitution’s Equal Protection Clause required that the children be given a basic education.
• In the Tenth Circuit, Tacy authored the briefs and delivered oral argument on behalf of a major health insurer, winning affirmance of summary judgment in favor of the insurer in a putative class action challenging the handling of claims for air ambulance services.

• Adler Planetarium — Board of Trustees
• NALP Foundation for Law Career Research and Education — Chair, Board of Trustees
• Impact for Equity — Board of Trustees
• American Academy of Appellate Lawyers — Elected Member
• Leadership Greater Chicago — Signature Fellow (Class of 2021)
• SidleyWomen — Chicago office co-chair

Tacy’s active pro bono practice encompasses the following:

• In a number of cases, Tacy has represented the interests of U.S. military service members and veterans. In Soto v. United States, Tacy took the podium in the U.S. Supreme Court to argue that a class of combat-wounded veterans should be paid Combat-Related Special Compensation for all months in which they are eligible. In the Ninth Circuit, Tacy represents a class of disabled veterans in Los Angeles arguing for affirmance of a judgment ordering the VA to provide housing on the West Los Angeles VA Medical Center campus. And in the D.C. Circuit, Tacy filed an amicus brief on behalf of a number of associations representing veterans and service members arguing in favor of expedited naturalization for active military. 
• Tacy has repeatedly played a leadership role in high-profile education reform litigation. She represented clients in litigation against the State of Michigan contending that it has violated the federal Due Process and Equal Protection Clauses by excluding students in certain Detroit schools from access to literacy. The case garnered national attention, and was discussed in legal and news publications including the ABA Journal, the New York Times, the L.A. Times, and others. Tacy was awarded “Litigator of the Week” honors by AmLaw Litigation Daily for her work on this case, with the article describing the case as “historic, “groundbreaking,” and “a remarkable victory.” Tacy was also recognized for her work in the Illinois Supreme Court on behalf of clients challenging the constitutionality of the state’s educational funding system.
• In a number of cases, Tacy has represented the interests of U.S. military service members and veterans. In Soto v. United States, Tacy took the podium in the U.S. Supreme Court to argue that a class of combat-wounded veterans should be paid Combat-Related Special Compensation for all months in which they are eligible. Tacy’s work on the case was profiled in Bloomberg Law. In the Ninth Circuit, Tacy represents a class of disabled veterans in Los Angeles arguing for affirmance of a judgment ordering the VA to provide housing on the West Los Angeles VA Medical Center campus. And in the D.C. Circuit, Tacy filed an amicus brief on behalf of a number of associations representing veterans and service members arguing in favor of expedited naturalization for active military.
• Working alongside The Shriver Center on Poverty Law and Legal Council for Health Justice, Tacy and a Sidley team won vacatur of the “public charge” rule promulgated in 2019. The rule would have allowed U.S. immigration authorities to deny adjustment of status for lawful immigrants who obtained even minimal public assistance. Tacy argued successfully in the Northern District of Illinois for a preliminary injunction, then argued successfully in the Seventh Circuit for affirmance of the injunction. Tacy and team subsequently won a final judgment permanently vacating the rule.
• Tacy, along with a team of Sidley lawyers, pursued a First Amendment challenge to a provision of the U.S. Leadership Against HIV/AIDS, Tuberculosis and Malaria Act, that requires non-governmental organizations to adopt a policy explicitly opposing prostitution as a condition of receiving federal funds. Sidley filed an amicus brief on behalf of a bipartisan group of nine current and former U.S Senators and Members of the U.S House of Representatives who were instrumental in the passage of the Act and/or its 2008 reauthorization. The brief challenged the government’s contentions that the Policy Requirement is permissible under the First Amendment. The Court agreed and held the Policy Requirement unconstitutional.
• She regularly serves as an instructor in the Supreme Court Practice law clinic at Northwestern University. Since 2006, Sidley has sponsored the clinic in which students help brief cases on the merits and identify court of appeals’ decisions as candidates for petitions for writ of certiorari, all in partnership with the firm’s pro bono program.
• In 2011, she was awarded Sidley’s Thomas H. Morsch Award for Pro Bono Achievement. The award was established to recognize and reward exemplary lawyers who choose public service work as a career. It is named after Thomas H. Morsch, a former partner at Sidley Austin, and a leader in the Chicago legal community who has championed the cause of public interest law for more than 40 years.