My son is applying at a major defense contractor. One of the questions ask's about drug use. Because he will undergo a polygraph for security purposes, how should he answer on the application? He has tried various drugs.

He needs to answer honestly. If he lies, his lies will be revealed in the polygraph. That will be 2 strikes - one for the drug use and one for the lying.

I agree... he needs to be honest. It may cost him the job... another reason to not do these things!