Asking advise on a matter that includes military law, civil service (federal) and the statute of limitations on an alleged fraudulant enlistment. Member is a federal civil servant with the Air National Guard, who was investigated by FBI approximately 20 years ago on unsubstantiated charges. Member took polygraph - now some of the answers given are being used to possibly revoke security clearance because they are inconsistant with statement signed concerning earlier drug abuse (member told FBI he did use drugs, but signed enlistment papers denying use). Questions - Can polygraph be used as evidence in formal military hearing or court on fraudulant enlistment? If member was not truthful in earlier admissions of drug abuse, can he be charged with obstructing the earlier investigation?