This paper attempts to analyze Rule 56 Summary Judgment of Federal Rules of Civil Procedure in terms of the change and development of purpose and operation over the entire history of the rule. The rule has two conflicting nature. One is the pursuit of efficiency and the other is, as a result of the first nature, the possibility of restricting people`s right to day in court. This two faced aspect of the Summary Judgment resulted in a three-part, cyclical change from emphasis on the efficiency of early 20th Century, through, post 1938 reformist period, limited use of the rule to the mid 1980s` active expansion of the use of summary judgment. Behind this change, there have been laissez-faire capitalism of pre-Depression period, and New Deal reform and liberal period of 1930s through to 1960s. Finally, as a result of explosion of litigation in the 1970s and conservative trends in the 1980s of American society, the Supreme Court change the course of summary judgment with Trilogy of Summary of 1986 expanding and supporting the use of summary judgment.