Believe it or not, that is not a simple question.  It is not simple because it depends on if the case goes to an actual trial or not.  A DUI can definitely be used as "leverage" when one is trying to negotiate and settle a case before it goes to trial.  However, once it is in trial then the question becomes does the DUI come in or not for the jury?  Unfortunately, the answer is "maybe".  The reason it is "maybe" is because it will not usually come in unless one wants to attack the credibility or character of the person who caused the DUI.  In other words, it does not come in just to come in...