미국법상 계약변경(modification)법리에 관한 비교법적 연구

Until now, modification of contract has been left to the free will of contract parties. In modern times, however, there are many contract modifications and the superior party has taken advantage of his status and has coerced the modification of contract to the other party. Since one of 2 parties of contract has more information for contract than the other party and the superior one has taken advantage of his superior status. Sometimes, they abuse their superior status and coerce unfair modification to the other party. In this case, the court should take step in and rule the fairness of modified contract. If the modified contract is not fair, the court should void the contract. The modification doctrine is a strong tool by the court when the superior party tries to manipulate the weak party and coerce the modification of the contract. The beauty of the U.S. modification doctrine is to secure procedure justice by asking the requirement of contract modification and to bring justice when the proving duress is very difficult. Since the burden of proof was belong to the party who tries to avoid modification(new agreement), it is very important for court to acknowledge the modification doctrine and give detail standards.There are 2 ways to secure fairness of modification of contract. 1) conclusion of contract phase(risk allocation by sharing the information of contract & asking consideration and good faith in contract modification), 2) the interpretation of contract(the court approve only when modification satisfy the requirements of consideration, good faith, fairness, availability of other options, etc.).