In Georgia can a collection agency garnish your husbands wages for an old credit card debt that was incurred before marriage that he knew nothing about?

That of course is why garnishment exists.

Noting the claim that he didn't know anything about it is a poor excuse (and entirely different than saying it he didn't incur it)...it certainly is his responsibility both for and to know what his credit and card is being used for. It clearly isn't the credit card company. Want to bet, the Credit company sent many, many bills and notices, phone calls, etc. before going the collection route? Obviously, the marriage doesn't change anything...except to say he maybe had more obligation to make sure the affairs of his prior life were resolved before wanting to leave them behind. Or perhaps you feel everything...that is all belongings and assets as well as debts from before the marriage are to be left behind for some reason?

At present four U.S. states - North Carolina, Pennsylvania, South Carolina and Texas - do not allow wage garnishment at all except for debts related to taxes, child support, federally guaranteed student loans, and court-ordered fines or restitution for a crime the debtor committed. Normally the maximum is 25% of wages.