He was the great-grandson of Founding Father John Jay, the 1st Chief Justice of the United States.

[1] Jay, who reportedly inherited his father's anti-slavery views, entered the United States Army at the beginning of the U.S. Civil War and served throughout the conflict, earning the rank of brevet Lieutenant Colonel and serving on the staff of General George Meade, Commander of the Army of the Potomac.

[3] After the War ended, Jay returned to Columbia where he entered the law school, graduating in 1868.

Jay focused his extensive practice on important trusts and estates as well as railroad an industrial matters.

Together, they resided at 22 East 72nd Street and the old family estate, known as Bedford House in Katonah, New York.

William and Lucie were the parents of:[8] Jay died of heart disease on March 28, 1915, at the Greenbrier Hotel in White Sulfur Springs, West Virginia.