Taylor was born in Schenectady, New York; his parents were John Bellamy Taylor and Marcia Estabrook Jones. One of his ancestors was Edward Bellamy. Taylor went to Williams College before enrolling at the Harvard Law School in 1928, where he received his law degree in 1932. He subsequently worked for several government agencies—in 1940 he became general counsel for the FCC—until he joined Army Intelligence as a major in 1942, where he led the group that was responsible for analyzing information obtained from German communications using Ultra encryption. He was promoted to Lieutenant Colonel in 1943 and visited Bletchley Park, where he helped negotiate the 1943 BRUSA Agreement He was promoted to full Colonel in 1944, when he was assigned to the team of Robert H. Jackson, which helped work out the London Charter of the International Military Tribunal (IMT), the legal basis for the Nuremberg Trials.
At the Nuremberg Trials, he initially served as an assistant to Chief Counsel Jackson and in this function was the U.S. prosecutor in the High Command case. The indictment in this case called for the General Staff of the Army and the High Command of the German Armed Forces to be considered criminal organizations; the witnesses were several of the surviving German Field Marshals. Both organizations were acquitted, though.
When Jackson resigned his position as prosecutor after the first (and only) trial before the IMT and returned to the U.S., Taylor was promoted to Brigadier General and succeeded him on October 17, 1946 as Chief Counsel for the remaining twelve trials before the U.S. Nuremberg Military Tribunals. In these trials at Nuremberg, 163 of the 200 defendants that were tried were found guilty in at least some of the charges of the indictments.
While Taylor was not wholly satisfied with the outcomes of the Nuremberg Trials, he considered them a success because they set a precedent and defined a legal base for crimes against peace and humanity. In 1950, the United Nations codified the most important statements from these trials in the seven Nuremberg Principles.
After the Nuremberg Trials, Taylor returned to the U.S. to a civilian life, opening a private law practice in New York City. He increasingly became concerned with Senator McCarthy's activities, which he criticized strongly. In a speech at West Point in 1953, he called McCarthy "a dangerous adventurer" and branded his tactics as "a vicious weapon of the extreme right against their political opponents" and criticized then-president Dwight D. Eisenhower for not stopping this "shameful abuse of Congressional investigatory power." He defended several victims of McCarthyism, alleged communists or perjurers, including Harry R. Bridges and Junius Scales. Although he lost these two cases (Bridges' sentence of five years of imprisonment was later voided by the Supreme Court), he remained unimpressed by McCarthy's attacks on him and responded by writing the book Grand Inquest: The Story of Congressional Investigations, which was published in 1955.
Taylor became a full professor at Columbia University in 1962, where he would be named Nash Professor of Law in 1974. In the mid-sixties, he was one of very few professors there who did not sign a statement by the Columbia Law School that called the student protests there beyond the "allowable limits" of civil disobedience. He was very critical of the conduct of the U.S. troops in the Vietnam War and urged president Richard Nixon to set up a national commission to investigate the conflict in 1971. He considered the bombing of Hanoi in 1972 "senseless and immoral" and heavily criticized the court-martial of Lt. William Calley (the commanding officer of the U.S. troops involved in the My Lai massacre) for not including higher-ranking officials. In December 1972, he visited Hanoi together with Joan Baez and others, amongst them also the associate dean of the Yale Law School.
He published his views in a book entitled Nuremberg and Vietnam: An American Tragedy (1970). He argued that by the standards employed at the Nuremberg Trials, the U.S. conduct in Vietnam and Cambodia was equally criminal as that of the Nazis during World War II.
In 1976, Taylor, who had already been a visiting professor at Harvard and Yale, also accepted a post as professor at the Benjamin N. Cardozo School of Law at the Yeshiva University, becoming a founding member of the faculty while continuing to teach at Columbia. His 1979 book Munich: The Price of Peace won the National Book Critics Circle Award for the "best work of general nonfiction". In the 1980s, he extended his legal activities into sports and became a "special master" for dispute resolution in the NBA. His 1992 700 page memoir of the Nuremberg trials (see bibliography) revealed how Goering "cheated the hangman" by obtaining poison.
Telford Taylor retired in 1994. He died in 1998 at the St. Luke's-Roosevelt Hospital in Manhattan after having suffered a stroke. He was survived by his wife Toby Golick and six children: Joan, Ellen, John, Ursula, Ben, and Sam.