美國法律的顯著特色即其反形式主義或反形式化傾向，它甚至使一位評論者質疑：今日的美國法是否還合適與英國法相提並論而放在英美法的標籤下。反形式化傾向主要表現在審判的層面，也就是本文的主題。本文將此傾向溯源至有所謂的美國法律之初始期，甚至更早的殖民地時期，藉以說明，此一傾向既是美國民族務實性格的表現，也是出於環境的事實需要。接著，本文指出美國法是在英國普通法的基礎上發展；繼受而來的現成法律時時面臨時空差異而待適應調整。調整既勢所難免，英美法的援例裁判方式——法律規則沒有文本(text)——亦為這樣的調整提供一方便之門徑。於是以荷姆斯為首的法律人，經由對「實定法在審判過程中如何表現」問題的重視，發展出關於審判的理論。這些理論轉而為法院之適用法律的態度提供了理論上的根據，進進一步強化了美國法律的反形式化傾向。在美國法理學與法理論的發展方面，法律工具主義也有母雞的地位：我們可以在當代美國種種法律思潮中，看到與現實法學與社會學法理學同樣的方法或目標或內容。

If there is one thing which we can use to characterize the American law, it must be its anti-formalistic tendency, which is so intense that one of its contemporary commentators has once raised the suspicion that there probably is no such thing as Anglo-American Law. The anti-formalistic tendency is primarily a feature that can be, and was indeed, discovered, in adjudication. That means that the tendency is not simply a matter of legal theory, but also is a way in which cases are approached and decisions made in court; it is a style of court practice-‘the grand style' in Llewellyn's terms. The author traced this tendency backg to its origin in the moment when the American law was in its initial stage. It then was further illustrated how this tendency has grown into a tradition, i.e., Legal Instrumentalism, as with the emergence of Holmes, and, under the name of Pragmatism, many other jurists and philosophers, in whose hands the first native American legal theory, Legal Realism, came to the fore. The author suggested that Legal Instrumentalism in American law and legal theory has the status of a hen, as it were, in the sense that only after a precise grasp of it can we begin to understand the practice of American law, and the subsequent multifarious developments of jurisprudence in the U. S.