Judge Winter was appointed United States Circuit Judge for the Second Circuit on December 10, 1981 and entered on duty January 5, 1982. He received a B.A. degree from Yale College in 1957 and an LL.B. degree from Yale Law School in 1960. He served as a law clerk to Judge Caleb M. Wright, Chief Judge, U.S. District Court, Delaware, 1960-61, and to Judge Thurgood Marshall, U.S. Court of Appeals, Second Circuit, 1961-62.

Judge Winter was a full-time member of the Yale Law School Faculty from 1962 until entering judicial service. At the time of his appointment, he was the William K. Townsend Professor of Law. He was also a Consultant to the Subcommittee of Separation of Powers, Committee on the Judiciary, U.S. Senate from 1968 to 1972, a Senior Fellow, The Brookings Institute, Washington, D.C. from 1968 to 1970, a John Simon Guggenheim Fellow from 1971 to 1972 and an Adjutant Scholar, American Enterprise Institute from 1972 to 1981.

He served from 1987 to 1992 as a member of the Judicial Conference Advisory Committee on Civil Rules. He served as Chair of the Judicial Conference Advisory Committee on the Rules of Evidence from 1992 to 1996. From July 1, 1997 to September 30, 2000, Judge Winter served as Chief Judge of the U.S. Court of Appeals for the Second Circuit. In April 1998, he was appointed to the Executive Committee of the U.S. Judicial Conference. From October 1999 to September 2000, he served as Chair of the Executive Committee. On October 1, 2000, he took Senior Judge status.

Judge Winter has received the Connecticut Law Review Award, Honorary Doctors of Law from Brooklyn Law School and New York Law School, the Federal Bar Council's Learned Hand Award for Excellence in Federal Jurisprudence, and the Yale Law School's Association's Award of Merit.