[james_s_tayler]

I was discussing this with a lawyer yesterday and she had something interesting to say about that.

At least in my jurisdiction both parties must act in good faith. This includes knowingly signing an invalid contract and blowing off some obligations in it on the premise that you didn't have to comply any way because it wasn't valid in the first place. In such cases it can be construed that you did act in good faith and a judgement made against you.