Mark Mosier

Mark W. Mosier

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Covington & Burling LLP
One CityCenter
850 Tenth Street, NW
Washington, DC 20001-4956
Tel: +1 202 662 5435
Fax: +1 202 778 5435




  • The University of Chicago Law School, J.D., 2004
    • with honors
    • University of Chicago Law Review, Comment Editor
  • The University of Chicago, A.B., 1997
    • with honors

Judicial Clerkship

  • Hon. John G. Roberts, Jr., U.S. Supreme Court, 2005-2006
  • Hon. William H. Rehnquist, U.S. Supreme Court, 2005-2005
  • Hon. Deanell R. Tacha, U.S. Court of Appeals, Tenth Circuit, 2004-2005

Bar Admissions

  • District of Columbia
  • Kansas

Mark Mosier represents clients in high-stakes, complex appeals in both federal and state courts.

Mr. Mosier has represented clients in more than 20 cases before the Supreme Court of the United States. He has filed briefs in many of the highest profile cases before the Court in recent terms, including the same-sex marriage, Affordable Care Act, and legislative prayer cases. He has also represented clients in more than 40 cases in federal courts of appeals and state appellate courts. These appeals have involved a wide range of legal issues, including administrative law, Alien Tort Statute, class actions, and insurance coverage disputes.

Before joining the firm, Mr. Mosier was a law clerk to Chief Justices John G. Roberts, Jr. and William H. Rehnquist of the U.S. Supreme Court, and to Judge Deanell R. Tacha of the U.S. Court of Appeals for the Tenth Circuit.

Representative Matters

  • Successfully represented Chiquita Brands International, Inc. in the Eleventh Circuit and Supreme Court in suits brought under the Alien Tort Statute arising out of extortion payments made by Chiquita’s former subsidiary to Colombian armed groups. Cardona v. Chiquita Brands Int’l, Inc., 760 F.3d 1185 (11th Cir. 2014), cert. denied 135 S.Ct. 1842 (2015).
  • Assisted in briefing in the U.S. Supreme Court the question whether the Anti-Injunction Act temporarily bars challenges to the Affordable Care Act. Nat’l Federation of Independent Business v. Sebelius, 132 S.Ct. 2566 (2012).
  • Successfully represented Eli Lilly and Company in the Second Circuit and Supreme Court in a major class action where plaintiffs sought billions of dollars in damages under the federal RICO statute. In re Zyprexa Products Liability Litigation, 594 F.3d 113 (2d Cir. 2010), cert. denied 131 S.Ct. 3062 (2011).
  • Successfully represented Family Dollar in the Fourth Circuit in a collective action suit under the Fair Labor Standards Act, in which former store managers sought overtime pay under the FLSA. In re: Family Dollar FLSA Litig., 637 F.3d 508 (4th Cir. 2011).

Previous Experience

  • University of Kansas School of Law, adjunct professor (2005)
  • San Francisco Giants, minor league baseball player (1997-1999)

Honors and Rankings

  • Washington DC Super Lawyers, "Rising Star" (2013-2014)
  • Legal 500 US, Supreme Court and Appellate (2015) 
  • Member of University of Chicago Athletics Hall of Fame (2005)

Pro Bono

  • Represented several religious organizations in filing an amicus brief in the Supreme Court arguing that communal prayers before town meetings violate the religion clauses of the First Amendment. Town of Greece, N.Y. v. Galloway, 134 S.Ct. 1811 (2014).
  • Represented political science professors in filing an amicus brief in the Supreme Court addressing the political power of gay men and lesbians in same-sex marriage cases. United States v. Windsor, 133 S.Ct. 2675 (2013); Hollingsworth v. Perry, 133 S.Ct. 2653 (2013).
  • Successfully represented the Respondent in a U.S. Supreme Court case that raised the question whether victims of domestic violence can pursue criminal contempt sanctions for violation of a protective order. Robertson v. U.S. ex. rel. Watson, 560 U.S. 272 (2010).

Memberships and Affiliations

  • Edward Coke Appellate Inn of Court

Publications and Speeches

  • Comment, “The Power to Declare Peace Unilaterally,” 70 University of Chicago Law Review 1609 (2003)
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