William “Will” Mattessich is a litigation associate whose practice focuses on international dispute resolution and commercial/civil litigation.

Mr. Mattessich joined Debevoise in 2016. From 2018-2019, he clerked for the Honorable Vanessa L. Bryant at the U.S. District Court for the District of Connecticut. Mr. Mattessich received a J.D. from Columbia Law School in 2016, where he was a Harlan Fiske Stone Scholar and a Managing Editor of the Columbia Journal of Transnational Law. Mr. Mattessich received his B.A. from the University of Iowa in 2012.

Mr. Mattessich is the author of “Digital Destruction: Applying the Principle of Non-Intervention to Distributed Denial of Service Attacks Manifesting No Physical Damage,” 54 Columbia Journal of Transnational Law 873 (2016). He is a member of the Bars of the State of New York and the State of Minnesota, and he is admitted to appear before the Southern and Eastern Districts of New York.


  • Columbia Law School, 2016, J.D.
  • University of Iowa, 2012, B.A.

Bar Admissions

  • New York
  • Minnesota