John Ellis Martineau was born in Clay County, Missouri. He graduated from the University of Arkansas in 1896 and obtained his law degree there in 1899. After graduation he served as a school administrator.
From 1902 to 1905 he served as a member of the Arkansas House of Representatives. He was appointed chancellor of the First Chancery Court in 1907 and served in that capacity until 1927.
While serving in that court he issued a writ of habeas corpus for defendants in the criminal prosecutions arising out of the Elaine Race Riot. Although the Arkansas Supreme Court later vacated that order, it allowed the defendants enough time to avoid execution and to seek habeas corpus relief in federal court. Their guilty verdicts were eventually reversed by the United States Supreme Court in its groundbreaking decision in Moore v. Dempsey.
Martineau was elected Governor of Arkansas in the 1926 election. Martineau was the first governor of Arkansas to broadcast his inaugural address on radio. The Martineau administration established a Confederate pensions board and authorized state aid to cities for highway construction through the Martineau Road Plan. In 1927, Martineau was forced to deal with a major crisis when the Mississippi River broke free of its banks and covered 13% of the state during the Great Mississippi Flood of 1927. Martineau was named president of the Tri-State Flood Commission. In the May of 1927, Martineau called out the National Guard in response to the lynching of an African-American prisoner by a mob of 2,000 to 5,000 people in Little Rock. The crime gained national notoriety.
Martineau never finished his term as governor, for on 2 March 1928, President Calvin Coolidge appointed Martineau federal judge for the United States District Court for the Eastern District of Arkansas. The appointment, recommended by then Secretary Herbert Hoover, stood in sharp contrast to the partisanship usually evident in the selection of a federal judge. Martineau served in this position until his death in Little Rock, Arkansas.
Martineau earned the reputation of fairness, integrity, and as a progressive politician. His role in state politics and effective management of crisis situations further secured his reputation as one of Arkansas best governors and brought him national attention.
Martineau was a member of the secret society, Knights of Pythias and the fraternal organization of the Freemasons
Martineau died in 1937 from Influenza and is buried at the Roselawn Memorial Park Cemetery in Little Rock.