Can I join the police force in my town if there is a DUI charge standing against me?

Formally speaking, you can become a police officer even if you have been charged with DUI. Practically speaking, it is almost impossible. Police departments give priority to candidates with a clean record. I would advise you to postpone your application and wait 7 years till your charges come off your record. Keep your affairs clean and stay away of your vehicle if you drank alcohol regardless of your career aspirations.