If you have any legal issues in your past, you can bet the house that you are going to be asked to explain what happened. The best and, only advise, that I can give you is to tell the truth and be prepared.
When speaking the truth about this legal past incident, you will need to acknowledge that you made a mistake and have learned from it. Be prepared to give examples in your life of how this has made you a more mature person. State examples of how this negative incident has helped you to make positive contributions in your life, family, workplace, and/or community. Show remorse for those that you hurt by your actions.
Now that you know there is no escaping this past legal incident, your task is to prepare an honest reply to the employer’s concern. So when you are questioned, there will be no hesitation, silence, stuttering or doubt in your voice. Remember to tell the truth.