As a cause of action or defense of cases, plaintiffs or dependants insist contracts or promises are not enforceable or void frequently because they are in restraints of trade, but don't prevail. I have collected all the cases made public since the Antitrust law went on effect here in Korea and researched them thoroughly. The research leads me to the conclusion as following. Firstly, it is too difficult to prove 'unreasonable restraint of competition', which is the most crucial requirement for unenforceability and invalidity of contract$. A bunch of economic analysis and empirical evidences are needed. Therefore, it costs a lot. Secondly, parties of cases are sure to have no sincerity and eagerness to carry out their burden of persuasion and proof. Especially if dependants raise several defenses including this affirmative defense, the defense is not almost always upheld. This paper is prepared to propose a solution to put aside this distress.
Reviewing cases as well as academic doctrines domestic and abroad, I come to a conclusion that a bare or naked promise not to incidental to trade and what the restraints are not fair under all the circumstances, should be struck down on the cause of unreasonable restraints. A checklist would be a good device to embody the unreasonableness, which, standing alone, is abstract and complicated. Is it greater that is required to protect the person on whose behalf the restraint is imposed? Does it impose undue hardship on the person restricted? Does it tend to create or have the purpose of creating a monopoly, the control of prices, or the artificial limiting of production? If we could answer yes to all the above questions, the promise would be held unreasonable.