Say an individual served in the military and separated after their enlistment under honorable conditions. For this enlistment, that person lied about not using drugs in high school. Now that individual wants to reenlist after being out of the military a few years. If that individual came clean about their previous drug use, could he face criminal charges for lying on the first enlistment?
They would not get in trouble for lying on the first enlistment.
But, it's possible they won't get reenlisted, and might have problems on getting a security clearance.
It would depend on the drug use, and whether it was a standard situation where the recruiter encouraged the lie.