He taught weapon systems and automotive engineering at the United States Military Academy and was the department's research officer.

In June 2004 Kern was chosen to head the internal military investigation of the Abu Ghraib torture scandal, also referred to as the Fay Report.

After retiring from the army in January 2005, Kern joined the Board of Directors of Agent Science Technologies,[3] EDO Corporation[4] and iRobot Corporation,[5] and is a member of the External Advisory Board of the University of Michigan Department of Mechanical Engineering, and a Senior Counselor of The Cohen Group.

[2] In 2007, Kern was elected a member of the National Academy of Engineering for bringing modern digitization technology to bear on military effectiveness, training, and procurement.

[6] Kern now serves as the Chair of Advanced Technology in the Department of Civil and Mechanical Engineering at the United States Military Academy.