James Diament Westcott III (June 18, 1839 – April 29, 1887), also known as James Diament Westcott Jr., was a Florida Supreme Court Justice, Florida Attorney General, and a member of the Florida House of Representatives.
Westcott was born in Tallahassee, Florida to James Westcott and Rebecca Sibley Bacon. His father was active in politics, helped write the first Florida Constitution and was one of Florida's first U.S. Senators while James Jr. was a child. James Jr. attended school in Tallahassee, mostly at West Florida Seminary. Although James Jr. was the third James D. Westcott, he used the "Jr." suffix throughout his life.
In 1858, Westcott became assistant secretary of the Florida Senate. The following year, he became a private secretary of Florida Governor Madison S. Perry. During the Civil War, Westcott was clerk of the Confederate States District Court for Florida. After the war, he was elected to the Florida House of Representatives in 1866 and was appointed state Attorney General in July 1868 by Governor Harrison Reed. Soon after, in 1868, an opening arose on the Florida Supreme Court and Governor Reed appointed Westcott making him the youngest justice in the court's history.
It was important for Reed to appoint a Democrat of Westcott's stature to offset the reputation other members of the Court had as carpetbagger Republicans. Westcott's friendly disposition on the one hand and thoroughness in researching the law and precedent on the other made in invaluable to the Court, and earned him respect from members of both parties. He wrote more decisions than any other Justice up to that time except for Chief Justice Randall.