Online trademark infringement and counterfeiting is a growing problem for luxury brands. In recent years, trademark owners have taken aim at the operators of online marketplaces and auction websites, asserting that these defendants are liable for contributory infringement due to sales of counterfeit goods on their sites. In addressing the scope of secondary liability for trademark infringement, the courts of the United States and European nations, including France, Germany, and the United Kingdom, have applied differing standards and reached inconsistent results. This article considers the question of secondary liability for trademark infringement from a comparative perspective and contrasts the rationales offered by the various courts in their decisions. It argues for a harmonization of the law across borders that also fits the realities of the online intermediary market business model, and proposes a standard for doing so.