在1992年之前，美國之電力事業具有垂直整合結構，此一結構使得大型電力公司同時經營發電、高度、電力輸送系統及地區配電公司，因為高壓輸送系統具有自然獨占之性質，故使控制高壓輸送系統之公司具有排除競爭之能力，若此一瓶頸設施無法開放提供其他市場競爭者使用，則批發電力市場即無法進入自由競爭，而使大型至垂直整合公司在其市場範圍內繼續具有獨占地位。在1978年公用事業管制政策法施行後，由第一市場模型進入第二市場模型，發電市場不再是獨占結構，且引進競爭後，經營效率有明顯提升，但因為FERC欠缺完整之授權，故批發電力市場仍無法進入競爭階段。在第二市場階段，反托拉斯政策所著重者為垂直整合公司對電力產業上下游市場之限制競爭行為。1992年能源政策法擴張FERC之強制代輸命令權，使其有權命令垂直整合公司開放聯通其高壓輸送系統為競爭者及第三人代輸批發電力，使其市場模型推進至第三市場模型，雖有學者倡議應再將市場推進至第四市場模型，即零售市場競爭模型，但其技術效率未必能使於第三市場模型。目前已有二十餘州完成電力零售管制之改革立法，並已開始實施電力零售之競爭機制，而在第四市場模型下，反托拉斯政策所應注意者則為水平市場力量之過度集中。經由對美國電力產業之觀察，電力產業應是一個可以藉由競爭之引進，而提高經營效率並提升消費者福利的產業，維持其由單一事業獨占，不僅不能促使其提高經營效率，更可能容許從事過度投資行為而傷害消費者福祉。

The domestic electric industry of the United States has a "vertical integration" characteristic, which means that IOUs operate generating, transmission, and distribution in a single uti8lity. Since the transmission system remains as natural monopoly, the IOUs could exclude competition by refusing open access of the transmission to competitors. After the PRUPA enacted in 1978, the domestic electric industry moved from Model-1, the Monopoly Model, into Model-2, the Monopsony Model. The generating market did not have natural monopoly characteristic since 1908s. After the PURPA introduced competition into generating market, the efficiency had been improved since then. However, the FERC did not have enough compelling wheeling authority to make the transmission open access to competitors; therefore, no competition exists in the wholesale market. In this stage, the antitrust policy focused on the vertical restraints. In 1992, the EPAct was enacted, which extended the wheeling authority for the FECT. The electric industry moved into Model-3, the Wholesale competition Model. By way of "functional unbundling" of the IOUs to create the ISO or ITC, the FERC tried to promote the wholesale competition. After PURPA and EPAct, the electric industry had been proved as an industry, industry, in which the competition could exist and might produce expected competition results. Under the wholesale competition model, the antitrust policy focus shifted to horizontal market power concentration. If the electric industry remains as monopoly structure, not only the efficiency cannot be improved, but also the final consumers might be suffered because the excessive investment by the IOUs. Now, there are many states enacted their electric regulation reforming act, which introduce competition into retail competition and those markets; therefore, moved into Retail competition model, the retail competition in electric industry would be a clear tendency.