An Assistant United States Attorney for the Eastern District of Oklahoma, Keen was actively involved in Native American affairs since receiving his Bachelor of Arts in History from Northeastern state University. He served as Executive Director of the Inter-Tribal Council of Nevada and the Director for the Bureau of Indian Services at the University of Utah. In 1972 Keen received his law degree from the University of Tulsa, where he graduated in the top 10 percent of his class. The former Business Manager of the Cherokee Nation of Oklahoma was one of the original Justices of the new Cherokee Court, being appointed by Principal Chief Ross Swimmer in 1977. In 1978 the Tribal Council named him the first Chief Justice of the Judicial Appeals Tribunal. Keen was again appointed to the bench in 1990 by Principal Chief Wilma Mankiller.
Biographical information taken from “The First Fifteen Years of the Cherokee Nation Judicial Appeals Tribunal” written by George N. Otey, III in 1990