2006年美國聯邦最高法院於eBay案推翻專利侵權案件推定核發永久禁制令之一般性原則，重新確立必須依照衡平法上四部測試法進行個案裁量。本文針對eBay案以來，美國法院對於專利侵權案件核發永久禁制令之基本態度與考量因素，透過現有文獻及實證調查研究其發展與演變，提供我國廠商在美進行專利訴訟之策略建議。後eBay時代可以區分為二個時期，第一時期為eBay案判決後至2008年底，美國法院在本期之中將四部測試法進一步具體化，在判決中陸續提出雙方當事人處於直接競爭關係、專利權人自行實施系爭專利等個別考量因素。對於具備這些考量因素之案件，法院傾向於核發永久禁制令。第二時期為2009年至2013年，美國法院對於四部測試法中之不可回復損害以及金錢賠償是否足以救濟專利權人所受損害等兩項判斷標準，開始逐漸放寬；對於專利權人自行實施系爭專利之重視程度則較前期下降。日落條款出現頻率增加，有利於侵權人取得迴避設計之緩衝期間。2012年開始出現的因果關聯要素，則增加專利權人取得永久禁制令的困難度。

In the eBay case of 2006,the Supreme Court of the United States overruled the then-current general rule granting permanent injunctions agaisnt infringement in patent litigations, holding that the courts should exert their discretion and use the traditional four-part test of equity to decide whether to issue permanent injunctions. This article is purported to provide useful strategies for Taiwan companies in facing patent litigations of the United States by investigating research literatures and conducitng empirical surveys, so that to find the trends of judicial decisions and factors influencing court’s decisions over permanet injunctions in the post-eBay era. The time following the eBay decision can be divided into two periods. The first period is from the eBay decision to the end of 2008. In this period, the courts specified several factors of consider ation on granting permanent injunctions, such as direct competition between parties in suit, patent holders practicing the inventions at issue, etc. The second period is from 2009 to the end of 2013. The courts loosed the standards of irreparable harm and whether monetary damage is adquate to compensate the harm. In comparison with the previous period, they no longer pay so much attention to the factor whether patent holders practice the inventions. The sunset provision was adopted more frequently to proffer the infringer a buffer time to design around the patent at issue in the case. The courts introduced in 2012 a new requirement—causal nexus—and in effect increases the difficulty for patent holders to attain permanent injunctions.