In 1920, while an undergraduate at Harvard University, he was expelled by its "Secret Court" of 1920 for associating with a group of homosexuals, including his roommate.
He was an Assistant United States Attorney for the Southern District of New York from 1925 to 1927 and again from 1931 to 1933, serving as Chief of the Criminal Division from 1931 to 1933.
[4] Lumbard was nominated by President Dwight D. Eisenhower on May 13, 1955, to a seat on the United States Court of Appeals for the Second Circuit vacated by Judge John Marshall Harlan.
[4] One landmark decision penned by Lumbard was Modern Settings v. Prudential (1991), which dealt with a dispute between an investor and a broker over alleged unauthorized trading.
"There will be instances where a disparity in sophistication between a brokerage firm and its customer will warrant a flexible application of such written notice clauses....
He declined a request from President Nixon to be the special prosecutor in the infamous Watergate scandal, a job that was later taken up by Archibald Cox.