Served on the Iowa Supreme Court from January 1, 1901, until December 31, 1912. For two years he was Chief Justice.
Born in Salem, Ohio, November 26, 1851. He came to Tipton, Iowa, with his parents in 1855. He was graduated from the Law Department of the University of Iowa in 1873. He came to Des Moines and practiced law until 1890, when he became dean of the law department at the University of Iowa. He continued as dean at the university until elected a Justice of the Supreme Court.
After his retirement from the court he moved to California where he was professor of law at Leland Stanford Jr. University. In 1914 he again became dean of the law department of the University of Iowa.
He was one of the commissioners who prepared the Code of 1897, He also authored numerous legal textbooks and was the compiler and editor of the Codes of Iowa known as "McClain's Codes".
Justice McClain died at Iowa City May 25, 1915.