Looking at the 2000s, the Supreme Court has no detailed research on legal issues, leave the judgment of the past and the trend seems to quote. For example, errors of law in the judgment of a legitimate reason, joint principal offender the functional activity of the dominant theory of criminal law theory, Studies of accumulated information, we accept them gradually is moving in the direction. But the Supreme Court include the specific criteria are difficult to understand the concept and are using them. Nevertheless, the fact that by missing arguments for the inclusion of judgment comes to the conclusion lacks a logical basis for a problem that is leaving. The concept of morals and social standards for the presentation of an abstract interpretation and judgment, collusion joint principal offender beliefs about the uncritical criticism of scholars for the future through careful research accumulated in Criminal Justice Studies, by accepting the theory and practice of will have to endeavor to harmonize. Thinking and knowledge learned in courses to apply it in practice will need to prevent useless. Korean Association of Criminal Case Studies is celebrating its 20th anniversary, criticism of the theory and practice through the mutual development to be able to look forward to continue to evolve.