James Buchanan Hays (September 10, 1838 – May 31, 1888) was an American attorney, politician, and jurist. He served 3 years as Chief Justice of the Supreme Court of the Idaho Territory (1885–1888), and earlier in his career served one term in the Wisconsin State Assembly (1867).

Born in Crawford County, Pennsylvania,^[1] Hays moved with his family to Ashippun, Wisconsin Territory, in 1847. He attended the University of Wisconsin and studied law in Horicon, Wisconsin. He married Permelia Elizabeth Hubbard (1844–1928) in 1863.^[2]

In Wisconsin, Hays served as Clerk of the Wisconsin circuit court in Dodge County, and was admitted to the Wisconsin Bar in 1865. While living in Juneau, Wisconsin, Hays served in the Wisconsin State Assembly in 1867.^[3] He then served as the district attorney of Dodge County in 1874. He was an unsuccessful candidate for Secretary of State of Wisconsin in 1877.

On July 1, 1885, Hays received a recess appointment as Chief Justice of the Idaho Territorial Supreme Court from President Grover Cleveland.^[4] He was formally nominated by Cleveland on December 14, 1885, and confirmed by the senate on October 2, 1886.^[5][6]

Hays died in Boise, Idaho Territory, while still in office^[7][8] and was buried in Wisconsin.^[9] Hays' eldest son, Samuel H. Hays, was a politician and attorney who served as the mayor of Boise, Idaho, and 29th Idaho Attorney General.