This article needs additional citations for verification. (August 2009) (Learn how and when to remove this template message)
Born in Fresno, California, Rowell graduated from Stanford University and Harvard Law School, and returned to Fresno in 1926 to open a private law practice there. He enlisted in the Army in 1943, where he studied occupation administration and also commanded troops in the Philippines.
Following Japan's surrender in 1945, Rowell moved to Tokyo and joined the occupation authority under Douglas MacArthur as Chief of Judicial Affairs. In this capacity, he worked with Brig. Gen. Courtney Whitney to prepare a draft constitution for the Diet of Japan to approve. Rowell extensively analyzed the existing Meiji Constitution, balancing it with the demands of Japanese lawyers to form a draft that was acceptable to both the Japanese government and the GHQ.