미국 민사소송절차에서 反訴의 제기가 강제되는 경우

There are two types of counterclaim in american civil procedure, the one is compulsory counterclaim and the other is permissive counterclaim. The latter form of counterclaim can be seen in Korea, but the former form is not familiar. Counterclaim is compulsory if it is met one of the four tests, ①same issues of fact and law, ②res judicata as test, ③same evidence as test, and ④logical rela-tion test. Compulsory counterclaim contributes to procedural economy and fair-ness, and so on. But if the defendant does not assert the compulsory counter-claim in former action, the claim cannot be asserted in later action by claim pre-clusion rule. Claim preclusion rule is different between Korea and U.S.A., so the principle of compulsory counterclaim cannot be permissive in Korea. But it would be also useful to us to analyse the rule.