David S. Mao

David S. Mao is an American law librarian who has served as the 12th librarian of the Supreme Court of the United States since 2024. Mao served as acting librarian of Congress from September 30, 2015, until the confirmation of Carla Hayden in 2016.

Early life David S. Mao was born in New York City and grew up in the Lawrenceville section of Lawrence Township, Mercer County, New Jersey, where he attended the Lawrenceville School. He completed his undergraduate studies with a degree in international affairs from the George Washington University in 1990, and subsequently earned a J.D. degree from Georgetown University Law Center in 1993 and a master's degree in library science from The Catholic University of America in 1998. On January 12, 2015, Mao was appointed to the deputy librarian of Congress office, by then-librarian of Congress James Billington.

As law librarian, Mao managed the operation and policy administration of the Law Library of Congress, which contains the world's largest collection of legal materials and serves as the leading research center for foreign, comparative, and international law. During his tenure as Law Librarian, he brought to the Library a copy of the 1215 Magna Carta for a historic exhibition on the eve of the charter's 800th anniversary.

Mao served as the first acting librarian of Congress from September 30, 2015, until the confirmation of Carla Hayden in 2016. He is the first Asian-American to hold the position.

In 2017 he became the chief operating officer of his alma mater, Georgetown University Law School.

In 2024, he became the 12th librarian of the Supreme Court of the United States.