What can the person do in such cases? And further more, what can the judge do to stop this paradox?
What if somebody copies your signature on a contract that says you can't sue them?
what can the judge do to stop this paradox?
I will assume that by "copying the signature" you mean "without the person's consent". In that case, the contract is void and consequently unenforceable. However, it would need to be proved that the person whose signature was unlawfully used did not intend to be a party to that contract.
For a contract to be valid, the parties must have knowingly and willfully entered it, whether it is via a document or through their subsequent conduct/actions. False pretenses, identity theft, and akin offenses preclude these two essential requirements of any contract. Moreover, if the person who forged the signature is a party to the contract, then that unlawful act clearly contradicts the prerequisite "covenant of good faith and fair dealing" that is presumed in contracts.
The remedies or actionability available to a person whose signature has been forged depend on the laws of each jurisdiction.
A fraudulent contract wouldn't be binding, but to take a different approach there's also the question of consideration. What did you agree to receive in return for agreeing not to sue the other party, and can the other party show that you received it?
From the link :
Consideration can be anything of value (such as an goods, money, services, or promises of any of these), which each party gives as a quid pro quo to support their side of the bargain. Mutual promises constitute consideration for each other.1 If only one party offers consideration, the agreement is a "bare promise" and is unenforceable.
Possible jurisdictional question (the link refers to English Law), but English Common Law gets around...