C.R.S. § 28-3-401

Except as otherwise provided in this article or by federal law, original enlistments in the military forces shall be for a period of three years and subsequent enlistments for a period of one or three years. The governor may by order fix shorter periods of enlistment or reenlistment for any of the military forces so far as not inconsistent with federal law. In the event of any emergency wherein the governor has called out any of the military forces, he or she may by order extend, for not exceeding the period of emergency and sixty days thereafter, the period of any enlistment in the forces called out which would otherwise expire.