Served on the Iowa Supreme Court from January 1, 1941, until December 31, 1958. He served as Chief Justice for two years.
Born at Cambridge, Illinois, October 11, 1889. He was graduated from the College of Liberal Arts of Drake University in 1912 and from the College of Law of the same institution in 1914. He began the practice of law at Adel but moved to Chariton the following year where he resided for many years. In 1916 he was elected County Attorney of Lucas County, a position he held for three terms. He served as a lieu- tenant during World War I. On July 10, 1930, he was appointed Judge for the then Second Judicial District Court where he continued to serve until coming on the Supreme Court bench. In 1935 he became a member of the Board of Trustees of Drake University. From 1947-1948 he was a presiding judge at the hostage case at the Nuremberg war crime trials.
After his retirement from the bench, Justice Wennerstrum engaged in the private practice of law at Des Moines. He died June 1, 1986, at age 96.