After graduation, Underwood clerked for Chief Judge
David L. Bazelon of the
U.S. Court of Appeals for the District of Columbia Circuit and then
Associate Justice Thurgood Marshall of the
Supreme Court from 1971 to 1972. After leaving the Court, Underwood was a
law professor for 10 years at the
Yale Law School, from 1972 to 1982. She also has taught at
Brooklyn Law School and at
New York University School of Law. Underwood left academia to work in the
Kings County District Attorney's Office. She later served in the District Attorneys for three different counties in
New York City: she was an Assistant District Attorney in
New York County, Chief of Appeals and Counsel to the District Attorney in
Kings County (Brooklyn), and Senior Executive Assistant District Attorney for Legal Affairs in
Queens County. She then served as Chief
Assistant United States Attorney and later Counsel to the
United States Attorney for the Eastern District of New York. In 1998, Underwood was appointed by
United States Attorney General Janet Reno to be Principal Deputy Solicitor General under
Solicitor General Seth P. Waxman. Underwood held that position for three years, and then served as
Acting Solicitor General from January to June 2001, making her the first woman to act as Solicitor General. After working in the U.S. Attorney's Office in New York for several years, in 2007 she was appointed Solicitor General of the State of New York, a position she held under three state Attorneys General. She has argued twenty-two cases before the U.S. Supreme Court, and many cases before the federal and state appellate courts. She became Acting Attorney General of New York on May 8, 2018, following the resignation of Eric Schneiderman. The State Legislature picked Underwood as the replacement to fill the remainder of Schneiderman's term on May 22, 2018. Underwood pledged not to seek elected office and fill out the remainder of Schneiderman's term until an elected successor is sworn in. As Attorney General, Underwood successfully sued
Donald Trump and his foundation,
Donald J. Trump Foundation, for "a pattern of persistent illegal conduct." The Attorney General's office passed to
Letitia James following her victory in the
2018 New York state elections. Underwood, who had never sought or held elective office, professed contentment when she returned to the Solicitor General's office in January 2019. On November 30, 2020, as Solicitor General of New York, Underwood argued the case
Trump v. New York on behalf of New York State. On November 3, 2021, as Solicitor General of New York, Underwood unsuccessfully argued the case
New York State Rifle & Pistol Association, Inc. v. Bruen on behalf of respondents. ==Honors and awards==