Vance was the nephew (and adoptive son) of 1924 Democratic Presidential Candidate and noted lawyer John W. Davis.
As Secretary of State in the Carter administration, Vance pushed for negotiations and economic ties with the Soviet Union, and clashed frequently with the more hawkish National Security Advisor Zbigniew Brzezinski. Vance tried to advance arms limitations by working on the SALT II agreement with the USSR, which he saw as the central diplomatic issue of the time. He was heavily instrumental in Carter's decision to return the Canal Zone to Panama, and in the Camp David Accords agreement between Israel and Egypt.
After the Accords, Vance's influence in the administration began to wane as Brzezinski's rose. His role in talks with People's Republic of China was marginalized, and his advice for a response to the Shah of Iran's collapsing regime was ignored. Shortly thereafter, when fifty-three American hostages were held in Iran, he worked actively in negotiations but to no avail. Finally, when Carter ordered a secret military rescue, Operation Eagle Claw, Vance resigned in opposition after the rescue attempt failed.
In 1997 he was made the original honorary Chair of the American Iranian Council.
Vance returned to his law practice at Simpson Thacher & Bartlett in 1980, but was repeatedly called back to public service throughout the 1980s and 1990s, participating in diplomatic missions to Bosnia, Croatia, and South Africa. He and Lord David Owen directly negotiated with Radovan Karadzic treating him like a fellow politician. They and the UN connived in maps and "peace plans" that gave Karadzic everything he had won by violence and tolerated the siege of Sarajevo. Vance's plan Z-4 was agreed to by the Croatian president Tudjman, but was rejected by the Krajina Serb leaders, even though it offered Serbs quite a large degree of autonomy, by world's standards. Being that the Serbs wanted no less than a full independence for Krajina, this was seen by Tudjman's administration as the best opportunity for returning the Krajina region back under the Croatian control. The opportunity was ceased by Tudjman by commencing the Operation Storm, a joint military mission of Croatian and NATO forces in 1995.
Vance also was a member of the Trilateral Commission.