She formerly headed the Supreme Court practice at the law firm Akin Gump Strauss Hauer & Feld.

Millett also was a longtime former assistant to the United States Solicitor General and served as an occasional blogger for SCOTUSblog.

[1] She authored the Solicitor General's brief in pathbreaking cases including Tennessee v. Lane (successfully defending the constitutionality of Title II of the Americans with Disabilities Act) and Nevada Department of Human Resources v. Hibbs (successfully defending the constitutionality of the Family and Medical Leave Act).

[8] At that time, the Fourth Circuit had four judicial vacancies, one of which was a seat generally thought to belong to Virginia, and all five candidates were among a larger group of individuals who had proactively submitted their information to the VBA and ostensibly hoped to be considered for a nomination to the Fourth Circuit by President Barack Obama.

On February 26, 2009, the Virginia State Bar separately deemed Millett to be "highly qualified" for the vacancy, along with Edwards, Keenan, and attorney Richard A.

[9] Keenan was nominated by President Obama to fill the vacancy on September 14, 2009, confirmed by the Senate on February 26, 2010, and sworn in on March 9, 2010.

On May 27, 2013, the New York Times reported that President Obama was considering nominating Millett to one of three vacancies on the United States Court of Appeals for the District of Columbia Circuit.

[25] In April 2018, Millett dissented when Judge Robert L. Wilkins’s majority opinion found that a Federal Trade Commission staff letter rejecting an earlier staff letter and concluding that use of soundboard technology violates the Telemarketing and Consumer Fraud and Abuse Prevention Act was not itself subject to judicial review under the Administrative Procedure Act.

[28][29] In December 2021, Millett wrote the majority opinion in a case brought by former president Donald Trump to block the release of presidential records that the congressional committee investigating the January 6, 2021, attack on the U.S.

[8] She is active in Aldersgate United Methodist Church and has a second degree black belt in Tae Kwon Do, according to her answers to a questionnaire for the U.S. Senate Judiciary Committee.