2018年美國聯邦最高法院首次將合理原則運用於雙邊市場中實現之垂直交易安排，美國運通案判決引發了反托拉斯學者和經濟學界的激辯。最高法院認為當市場兩組參與者需同時參與才能進行交易時，相關市場就包括平台的雙方。由於跨邊網路效應的緣故，平台一側的價格上漲不得作為具有反競爭效果的證據。又美國聯邦最高法院遵循美國聯邦最高法院將品牌間競爭作為反托拉斯主要關心目標之判決走向，將關注重點聚焦於美國運通於信用卡市場中與VISA、MasterCard、Discover等信用卡平台間之競爭。認為信用卡市場存在品牌間競爭時，即便反勸誘條款確實具有反競爭效果，該競爭不利益也能夠被市場競爭所稀釋。本文除了針對各級法院審查所提出之理由進行分析討論外，亦針對雙邊市場競爭分析之迷思進行討論。美國最高法院多數意見長久受到芝加哥學派的影響，認為唯有品牌間競爭受到損害才需要介入市場競爭。然而以美國運通案為例，即使信用卡市場中具有激烈的品牌間競爭環境，受到市場競爭現實和產品異質性影響品牌間競爭對美國運通的品牌行為牽制力將被削弱。因此本案應重新重視品牌內競爭可能帶來之效果，重新審視雙邊市場競爭分析之迷思對競爭分析所帶來之影響。;The Supreme Court’s decision which made in the American Express case, is the only U.S. antitrust case that has explicitly addressed the unique issues raised by so-called platform or multi-sided markets. And the decision might tell us about the attitudes of the Court’s five-Justice majority about antitrust law. As had the Second Circuit, the majority relied heavily on a discrete body of academic literature regarding two-sided platforms to define credit card networks as a special type of two-sided platform known as a transaction’ platform. The Court then reasoned the key feature of transaction platforms is that they cannot make a sale to one side of the platform without simultaneously making a sale to the other. The Court also maintained that two-sided platforms exhibit indirect network effects, which means the value of the services that a two-sided platform provides increases as the number of participants on both sides of the platform increases. The majority thought the plaintiff had to provide evidence that the overall “transaction” price of the platform′s services had increased, otherwise there’s no reason show that the agreeing with Amex increase anticompetitive effect. According to the majority’s inference, the loss of intra-brand competition can only be problematic if inter-brand competition is limited. There’s no need to worry when the intra-brand competition exists. The purpose of this study was to show that even if there’s competition in credit card market, American Express still have market power to force the merchant accept their service. Since the competition in credit card market can no longer tie up the companies behavior, it is necessary to recheck vertical restraints which is about interbrand competition. And rethinking the two-sided market competition analysis.