Mark Mosier co-chairs Covington’s Appellate and Supreme Court Litigation Group.

A former law clerk to Chief Justices William Rehnquist and John Roberts, Mark has represented clients in more than 60 cases before the U.S. Supreme Court. Mark argued and won U.S. ex rel. Polansky v. Executive Health Resources, an important False Claims Act case the Court decided last term. Mark has represented clients in many of the highest profile cases before the Court in recent terms, including the travel ban, same-sex marriage, the Affordable Care Act, partisan gerrymandering, and legislative prayer cases.

Mark also frequently represents clients in federal and state courts of appeals. These appeals have involved a wide range of legal issues. He also advises clients on litigation strategy before the case reaches the appellate stage. He works closely with the trial team to ensure that issues are properly presented and preserved for appeal and, when necessary, to develop novel legal arguments that can help shape unsettled areas of law.

Mark is also a co-founder of the ChadTough Defeat DIPG Foundation. This non-profit organization was started after his six-year-old son, Michael, passed away from DIPG, the deadliest form of childhood brain cancer. Since its founding in 2015, the foundation has funded more than $20 million for DIPG research.