If a judgment has been filed against you what can they do legally to collect the debt?
Depends on what state you are in. Some states allow a creditor to garnish your wages or take the funds from your bank account. Of course, the creditor would have to know your bank info. or employer to do this. Some states also allow collection against your assets, i.e. home. It just depends on what state you are in. In Texas, where I practice, a home is non-exempt from collection and wage garnishment is only allowed in child support cases. I do not know what state you are in to advise you specifically.
Collecting on a judgment is a long process and is usually very hard work for the creditor b/c they have to find out what your assets are, where you work, which bank you use, etc. Depending on the amount of the judgment, it may or may not be worth it for the creditor to incur the expense of collection. It depends on the amount of the judgment and the creditor.
I would consult a local attorney or bankruptcy attorney that is familiar with the collection laws in your particular state.