Roy J. Epstein


The 2011 decision by the Federal Circuit in Uniloc v. Microsoft properly condemned the “25% Rule,” which bases a reasonable royalty on 25% of an infringer’s profits. Nonetheless, at least one proponent of the Rule continues to argue that the Rule is fundamentally valid and should remain in use. This article analyzes the historical development of the Rule, its conceptual basis, its application in actual cases, and relevant insights from other recent Federal Circuit cases. Each analysis shows fundamental problems and contradictions that demonstrate the Rule can never be a reliable patent damages methodology. There is no reason to change the conclusion in Uniloc.