本文篩選公平交易委員會成立以來，具有代表性之聯合行為檢舉案例計109件，就產業結構、產品特性、進入障礙、成本結構差異、市場區隔、生產方式及消費者習慣等各項因素，以Probit之計量模型分析影響公平交易委員會對於個案是否處分之因素，俾提供公平交易委員會作為判定聯合行為是否違法之基礎。實證結果顯示，公平交易委員會施政對聯合行為有甚高之過阻效力。但是，隨著公平交易委員會對相關聯合行為處分案件之不斷累積及密集宣導，國內事業亦已同時暸解公平交易委員會對聯合行為之處理多以書面之文字協定為處分之主要依據事證，故宮即令有聯合行為之存在，亦多轉向為不留任何書面之口頭協議，甚或不存在任何直接的意思聯絡之默契性的「一致性行為」，形成公平交易委員會處理聯合行為之瓶頸。此一困難，亦嚴重困擾先進國家之反托拉斯法執法當局，目前各國均已力謀因應之道，期建立處理一致性行為之執法制度，其作法及經驗甚值我國參考。

We choose 109 complaint cases about collusion behaviors dating from the establishment of the FTC. We use these samples and build a probit model to analyze the effects of structural factors such as, concentration ratio, product characteristics, entry barriers, cost differences, market segmentation, production technique and consumer tastes, on the decision made by the FTC. The evidences show that the FTC implementation is effective to block the collusive behavior. However, after many cases being punished by the FTC, the enterprises also understand that the FTC generally uses the written agreement as the criterion to judge if the defense break the law or not. Thus, it is imperative that enterprises turn to the concerted practices as a way to implement the collusive behaviors without being any explicit cooperation or written agreement between the colluders. This is the so-called tacit collusion in the field of the industrial economics. This state of affairs happened in Taiwan as well as the rest of the world and severely embarrasses the competition authorities. In order to overcome the difficulty, US and European countries are trying hard to establish the criterion or institution to deal with tacit collusion. Their experiences could be used for us to deal with the similar cases.