Credit card collection, medical bill collection

If it's still at the trial stage then normally yes. Once an actual judgement has been granted it becomes harder although not impossible.

Of course, it's difficult to give exact advise with out further details.

I was told that I have several judgements against me for past credit card bills and one was a medical bill. I have never received any documentation of this nor was I informed of a summons. I have moved from the state where these bills were and received no paper work even though I put in a change of address. Can I fight this in any way?

Put in a change of address where? If just the PO, forwards expire after a few months. No, you don't stand a chance. All they have to do is prove that they mailed bills to your last known address.

Who is telling you this?

If you have a real judgement and they could not find you ( forwarding address at post office expire in one year) so if you did not notify the lender where you were at, they may not have known)

So the judgement may be valid, you will have to file a motion in the court where they were done, appear and try to prove you were not notified properly. If they could not find you, all they have to do is post this in the newspaper.