Gregory Tsonis


  • Gregory Tsonis
  • Phone: +1 312 499 6779

    Import to Address Book

  • Duane Morris LLP
    190 South LaSalle Street, Suite 3700
    Chicago, IL 60603-3433

Gregory "Greg" Tsonis is an integral member of the Workplace Class Action Group at Duane Morris. With a practice that encompasses defending companies in a wide spectrum of employment law cases, Mr. Tsonis adeptly handles everything from complex, high-stakes class actions asserting wage & hour and discrimination claims to intense individual plaintiff cases and government agency investigations.  His clients span a variety of sectors, including retailers, healthcare providers, insurance agencies, logistics companies, staffing agencies, senior living facilities, product manufacturers, and tech companies.  While he has defended several high-profile cases for Fortune 500 companies, Mr. Tsonis also prides himself on his strategic defense of small to medium-sized businesses throughout the Midwest. 

Mr. Tsonis has experience in all phases of litigation, including federal trial court experience.  He regularly appears in state and federal court, arbitration proceedings, and in front of government agencies.  His knowledge extends to a broad spectrum of federal and state statutes, including the Fair Labor Standards Act, state wage & hour laws, the Civil Rights Act, the Americans with Disabilities Act, the Biometric Information Privacy Act, and state consumer protection laws, among others.  In 2024, Mr. Tsonis was recognized in the peer-nominated Best Lawyers as “One to Watch” and as a Super Lawyers “Rising Star” for Labor & Employment, which is awarded to only 2.5% of attorneys in Illinois.

Mr. Tsonis brings a unique perspective to his legal practice, having spent over a decade working in the business world for a national retailer, including multi-store management roles, before transitioning to law. This extensive experience in business management provides him with a deep understanding of the challenges businesses face and companies’ priorities, enabling him to craft tailored legal strategies that align with his clients' objectives.  Through his combination of legal expertise, business acumen, and dedication to client success, Mr. Tsonis has become a trusted advisor to companies navigating the complexities of employment law, helping them solve problems big and small alike.

As a relentless advocate for his clients, Mr. Tsonis is invested in staying at the forefront of emerging legal issues that impact employers. He dedicates himself to mastering new areas of law, from navigating the complexities of compliance with Illinois' amended Day and Temporary Labor Services Act to addressing the evolving legal implications of adopting artificial intelligence technologies in the workplace. This forward-thinking approach ensures that his clients are well-prepared to mitigate risks in today’s rapidly changing legal landscape.

Mr. Tsonis received his Bachelor of Arts degree from the University of Chicago, and received his law degree, with honors, from the University of Chicago Law School. During his tenure at the University of Chicago Law School, he served as Comment Editor for The University of Chicago Legal Forum.


  • Illinois
  • U.S. District Court for the Northern District of Illinois
  • U.S. District Court for the Central District of Illinois
  • U.S. District Court for the Western District of Tennessee
  • U.S. District Court for the Eastern District of Michigan


  • University of Chicago Law School, J.D., with honors, 2015
  • University of Chicago, B.A., 2005


  • Duane Morris LLP
    - Associate, 2022-present
  • Seyfarth Shaw LLP
    - Associate, 2021-2022
  • Kirkland and Ellis LLP
    - Associate, 2015-2021

Professional Activities

  • Hellenic Bar Association

Honors and Awards

  • Named to Best Lawyers "Ones to Watch," 2024

Civic and Charitable Activities

  • The Hellenic Initiative/Pan Hellenic Scholarship Foundation

Selected Publications