What Type of “Drug Use History” Would Disqualify Someone During a Background Check?

Question by Face on Fire: What type of “Drug Use History” would disqualify someone during a background check?
I am scheduled to take the written and physical tests for the Santa Clara County’s sheriff’s dept. this Saturday, however I noticed that the #1 reason people fail the application process is because of “Drug Use History”, it says (1-5 years depending on the substance). I have not been perfect my whole life and was wondering if anyone knew what they are looking for.

Best answer:

Answer by tentoes
They want to know if you’re lying and two, if they suspect that you are, they can test your hair. Be honest.

Know better? Leave your own answer in the comments!