Decius S. Wade was born in Andover, Ohio, January 23, 1835, the son of Charles H. and Juliet Spear Wade. He was educated in local schools, studied law with the firm of his uncle, Senator Benjamin F. Wade, and was admitted to the Ohio Bar in September 1857. He practiced law at Jefferson, Ohio, until 1860, when he was elected probate judge for Ashtabula County. He held this position until 1867. Wade was elected to the Ohio State Senate in 1869, and... served until 1871, when his appointment as Chief Justice of the Supreme Court of Montana Territory was confirmed.

Decius Wade's appointment to the Supreme Court can be traced to his family's influence with the national Republican administration. Two of his uncles, Edward and Benjamin F. Wade, were multi-term members of Congress, and his first cousin, Nellie Wade, was the wife of Schuyler Colfax, Vice President in the Grant Administration.

Wade's Supreme Court appointment was extended three times. At the end of this service in 1887, he began the practice of law in Helena, Montana. When Montana achieved statehood, Wade was appointed to the Codification Commission to systematize laws for the new state. He again returned to private law practice in 1892. In 1895, Wade and his family returned to the family farm, "Little Medford," near Andover, Ohio, where he retired.

Bernice Galpin and Decius S. Wade were married June 3, 1863. They had one child, Clare Lyon Wade. Their daughter graduated from Wellesley in 1890 and later married William E. Safford, a noted government botanist.

Decius S. Wade died at his home in Andover, August 4, 1905.