Illinois will not issue you a teaching certificate with a DUI on record.
Strangely, if you are 'certificated'/ teaching and happen to get a DUI, you may get a 'reprimand' from your employer (district), or you may get nothing at all, it depends.
In one of our neighboring districts a driver education/PE high school teacher received a DUI. He was taken off his driver ed duties and given PE classes full time. No other disciplinary actions were taken by the school board.