Contractor extortion?

[justadad]

Have a contractor who has been paid to complete the next installment of our home improvements. The contractor was fined by the County (in Georgia) for building without a permit. He will not return to complete the work unless I, as the homeowner, pay the fine for him. How does this affect the contract that he has signed and agreed to? Do I have a case against him for some kind of extortion as the payment of the fine is being used as a work stoppage threat against me?