You have never been convicted of anything (as municiple ordinances are not criminal). You can say no...you wouldn't say you have been convicted of parking ticket which is the equivalent. No, they can't discriminate but it is very hard to prove that is why you didn't get the job.
The safest way to answer is "I have never been convicted of any crime"
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If the job requires drug testing, it seems like the employer would have a good argument that prior drug arrests are relevant to the job you are applying for, and concealing one they can easily find out about doesn't sound like a prescription for success. As you have correctly concluded, you need to answer the questions as asked. Were the charges issued as forfeitures, or did you plea bargain down from misdemeanors? Since the case shows up on CCAP, it's a fair bet that even a cursory background check will reveal it. You may wish to consider a "no, but..." answer that discloses an incident they are likely to find out about anyway. If you do wish to consult a lawyer, this is an employment law question, not a criminal defense question.
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