Here is a couple of approaches which should work well together: First make bail proportionate to your ability to pay. Thus if you are an otherwise destitute criminal, and you get caught committing a crime, you'll be released on your own recognizance the same day so you can quickly get back to work.
Second up is a law that makes information on anyone who calls 911 available to the defense attorney for the criminal who was caught doing something naughty. Thus the criminal will have the name, phone number, and home address of whomever called 911 and ratted him or her out. This should help immeasurably in putting together a strong defense a la H. Clinton. If you can't find the witness, you won't get convicted.