Andrew Lyonsberg focuses his practice on litigation in the Supreme Court and appellate courts across the country, as well as major motions at the trial-court level. He has briefed more than fifty appellate matters and dispositive motions, and has argued before the US Courts of Appeals for the Fifth and Sixth Circuits. Andrew also has extensive experience with agency litigation under the Administrative Procedure Act, including several recent victories setting aside federal agency action.

Andrew was recognized as a recommended lawyer in Supreme Court and appellate litigation by The Legal 500 (2021), with clients praising his “big-picture thinking” and “sophisticated view on how the executive branch operates.”

Before joining McDermott, Andrew served as a law clerk to the Honorable Kim McLane Wardlaw on the US Court of Appeals for the Ninth Circuit. While in law school, he was a forum editor of the Yale Law Journal.


  • Obtained a Supreme Court victory expanding judicial review over administrative decisions on Convention Against Torture claims. (Nasrallah v. Barr)
  • Won a complex statutory-interpretation decision in the Supreme Court securing a favorable construction of the Immigration and Nationality Act. (Guerrero-Lasprilla v. Barr/Ovalles v. Barr)
  • Obtained a permanent nationwide injunction on behalf of a consortium of leading colleges and universities, blocking an immigration policy detrimental to the interests of international students. (Guilford College v. Wolf, M.D.N.C.)
  • Helped secure a Supreme Court win in a case that significantly narrowed the administrative law doctrine of Auer deference. (Kisor v. Wilkie)


  • The Legal 500 US, Appellate-Courts of Appeals/Appellate-Supreme Courts, 2021


Yale Law School, JD, 2016
Williams College, BA, magna cum laude, 2011

District of Columbia

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