There is no valid answer in terms of percentages. However, without an attorney your choice when faced with the charge is either guilty or not guilty. Only problem with the "not guilty" plea without an attorney is then what, conduct a jury trial pro per? Although no guarantee, having an attorney negotiate the offense down or ultimately litigate the unjust charge through a jury trial, you will probably be much better off particularly since it sounds like you have a possible defense and a...