Ralph Earle 2d, a Philadelphia lawyer who became lead negotiator in the SALT II arms control talks with the Soviets during the Carter administration, died Monday, Jan. 13, of complications from Parkinson’s disease at a hospital in Sarasota, Fla. He was 91.

A career arms control expert with the title of ambassador, his public service spanned four decades and the terms of five presidents. He had retired to Manasota Key, Fla., at the time of his death, although earlier he had lived in Haverford and Washington.

Born in Bryn Mawr, Ambassador Earle was the son of former Pennsylvania Gov. George H. Earle 3d and Huberta Potter Earle Sheaffer. He attended Episcopal Academy and graduated from Deerfield Academy in Massachusetts.

He was a graduate of Harvard College and Harvard Law School and served in the Army during the Korean War. Following law school and a clerkship with a federal judge, he worked for 15 years at the Philadelphia law firm of Morgan, Lewis & Bockius, where he became a partner.

In 1968, he was appointed to be principal deputy assistant secretary of defense in the office of International Security Affairs at the Pentagon, a high-ranking post in which he reported to the U.S. Secretary of Defense. He was appointed during the Lyndon B. Johnson administration and stayed on when Richard Nixon took office in January 1969.

From 1969 to 1972, he was the defense adviser to the U.S. mission to NATO, the “No. 3 person” on that delegation, he told an interviewer for the Association for Diplomatic Studies and Training Foreign Affairs Oral History Project much later, in 1991.

“I then returned to the private practice of law in Philadelphia but was asked to be a consultant to the SALT II delegation, and made several trips to Geneva during 1972,” Ambassador Earle recalled. “It was very exciting, to think of sitting across the table from the Soviet Union. The only real, live Soviet I'd ever seen was a major in Berlin. And I was thrilled.”

In the summer of 1973, he became a U.S. Arms Control and Disarmament Agency (ACDA) representative on the SALT II delegation. (The ACDA was an independent agency of the U.S. government. It sought to ensure that arms control was integrated into the development and conduct of national security policy.)

In 1977, when Carter took office, Ambassador Earle became the alternate to ACDA delegation chief Paul Warnke. When Warnke resigned a year later, the ambassador was made head of the delegation, and remained in that role through June 1979, when the SALT II treaty was signed.

The second Strategic Arms Limitation accord established numerical parity between the U.S. and the Soviet Union in the area of nuclear weapons delivery systems. It also limited the number of missiles with multiple, independent nuclear warheads.

Though both sides signed the pact, it was never ratified by the U.S. Congress. In December 1979, the Soviets launched an invasion of Afghanistan, effectively killing any chance of passage.

Carter withdrew the treaty from the Senate in January 1980. During the early 1980s, both nations agreed to respect the pact, but it was allowed to expire on Dec. 31, 1985.

In January 1980, Ambassador Earle was appointed director of the Arms Control and Disarmament Agency. He served until just before Ronald Reagan was sworn in as president on Jan. 20, 1981. He later rejoined the agency in 1994 and retired in 1999.

He was active in arms control organizations, including the Lawyers' Alliance for World Security, and he lectured and wrote on arms control for many years.

Ambassador Earle will be remembered for his sharp intellect, his good humor, and his patriotism, his family said in a statement.

He was a skilled storyteller, a voracious reader, and a Sherlock Holmes fan. He rejoiced when the Philadelphia Eagles won the 2018 Super Bowl.

He was married to Eleanor Forbes Owens. They had five children before divorcing. He was married again to Julie von Sternberg. Both survive.

In addition to his wife, he is survived by children Eleanor Earle Mascheroni, Ralph Earle 3d, Duncan Owens Earle, Amanda Earle Ciccarelli, and Caroline Earle Walsh; and nine grandchildren.

Plans for a memorial were pending.

Contributions may be made to PBS via https://www.pbs.org/, or the ASPCA via https://www.aspca.org/.