聯合行為向來為公平交易法所規範之行為中相當受到矚目的類型。聯合行為對相關市場產生限制競爭效果，扼殺原本應該由各事業依自己商品或服務之品質、價格等因素進行之公、自由之競爭。本文所要論述的是九家民營電廠（ Independent Power Producer，一般簡稱IPP）之間，與台灣電力股份有限公司有關協商購售電價格之案例。本案的特殊性在於電力市場目前尚未完全自由化，並有主管機關經濟部能源局與電業法之存在，因此對於公平交易委員會適用公平交易法介入本案的正當性受到質疑。再者，九家民營電廠是否具競爭關係而構成發電市場，透過合意共同拒絕與台電公司進行協商，是否影響市場供需功能，皆是判斷聯合行為成立與否之重要議題。

Concerted action is a type of act that has caught reasonably great attention under the Fair Trade Law. Concerted action has generated a restrain competition effect on the relevant market to strangle the quality, prices and other factors that originally supposed to be borne by each enterprise to perform fair and freedom of competition. The purpose of this paper is to study a power purchase agreement case between nine independent power producers (generally referred to as IPPs) and Taiwan Power Company (Taipower). What so special about this case is that to date, the power market has not been fully liberalized and there are the existences of Bureau of Energy, Ministry of Economic Affairs and the Electricity Act. So, the legitimacy of Fair Trade Commission to intervene in this case by using the Fair Trade Law has been questioned. Furthermore, whether or not these IPPs possess a competitive relationship to form a power generation market, and whether or not their refusal to negotiate with Taipower through an agreement would result in an impact on the market function with respect to production, trade in goods or supply and demand of services are important issues to determine whether or not competing enterprises establish the concerted action.