What kind of "drug usage" are we talking here? Were you ever arrested and convicted? As far as I'm concerned if you have no convictions and it's not on your record don't say ****. While I don't believe in lying I also don't believe in judging a man based on his mistakes. So you did a little blow and puffed some on the magic dragon when you were younger. Hell I'd guess Vanguard has done that and look how christian he is now. We all do stupid **** when are young but we learn and grow from our mistakes. If a department won't take you because you've done drugs that's their loss. I've had sherrifs that worked at my highschool that were 100 percent honest and said they've done pot when they were younger. Hell as far as I'm concerned anyone age 40-50 has more than likely done pot, and anyone ages 15-30 still does pot.
Some places are just picky and if they have a bunch of applicants they can get away with it. If there are no conviction then some departments look the other way because they know how it is, I know a lot of officers who won't right tickets of misdemeanor marijuana possession unless you P.O.P. Could always look federal, I know the CBP didn't ask jack as far as drug usage on their application, more interested if you would be willing to shoot someone.