rossn12,
Remeber that the departments expect for you to be human. We have all made mistakes, and they don't expect you to come in with a flawless background. Things that you have done when you were younger probably will not be weighed as heavy as the mistakes that have most recently occured. Most departments have a policy that if you haven't smoked marijuana with-in the last year you won't be disqualified. The only thing you must remeber is that all departments have a cut-off as to what they consider "experimentation". What I understand is that police departments normally have a higher cut-off than, say for instance, the FBI. The FBI states that more than 15 times is an automatic disqualifier. The police departments tend to be a little more protective of their cut-off information. I think they feel that if they tell the number, then people will lie, but if they keep a secret, they can better make a decision on whether to keep you or not. My advice is to continue NOT smoking marijuana, and don't worry too much about mistakes you made when you were a kid. Study this website and be ready for the polygraph, and I'll bet everything will fall into place.