DETROIT � Caleb Campbell will not get a chance to play for the Detroit Lions because of a change in military policy.

Campbell was a seventh-round draft pick for the Lions in April. At the time, Army policy would have allowed the West Point graduate to serve as a recruiter if he made the team.

But a subsequent Department of Defense policy has superseded the 2005 Army policy.

In a letter to Lions president Matt Millen dated Wednesday, U.S. Army Lt. Col. Jonathan P. Liba wrote that Campbell has been ordered to give up professional football for "full-time traditional military duties."

Liba wrote that 2nd Lt. Campbell may ask to be released from his active duty obligations in May 2010.

Liba said Campbell was allowed to enter the draft "in good faith."