Ehrin began his law enforcement career serving the Tennessee State Parks and later joined the Tennessee Highway Patrol. While working as a law enforcement officer, he served as a liaison to the Tennessee Emergency Management Agency and was later appointed as the FirstNet Authority single point of contact and deputy statewide interoperability coordinator for Tennessee. Ehrin remains a commissioned police officer, training new officers and assisting search and rescue operations, natural and man-made disaster response, emergency medical response, interpretive programming, and wildland fire-fighting.