The best way is to send letter to all the credit bureaus explaining them the situation and providing them with the documentary proof. Once you establish that, it would improve your credit score. Further, see if this judgment is more than 5 years old, and can be taken out of the credit reports. A debt can always be negotiated. Pick up the phone and call the last debt collection agency, and propose to them a very small amount. They would always counter it. You can improve your initial offer, and then negotiate it. Finally, one of you would blink. Best thing is always to see an attorney, they know all these tactics, especially the licensed one.
Only see a licensed attorney before you make any decision. This answer may not be perfect in any given situation.