Abstract: This article explores the process of emergence and practical implementation of the “Manifest Disregard of Law” Doctrine as the grounds for cancellation of arbitration decisions rendered in accordance the rules of Financial Industry Regulatory Authority of the United States (FINRA). The content of the doctrine is formulated by the Supreme Court of the United States. De jure, it is not one of the bases for cancellation of arbitration decisions stipulated by the Sector 10 of the Federal Arbitration Act of 1925; de facto, this doctrine constitutes a new independent basis for such cancellation. The scientific novelty consists in the fact that the “Manifest Disregard of Law” Doctrine has not been examined within the Russian legal science, excluding the instances of brief mentions. The conclusions is made the revelation of facts of the “manifest disregard of law” by the arbitrators does represent independent grounds for cancellation of arbitration decision along with other grounds established by the Federal Arbitration Act of 1925. At the same time, practical application of such grounds by the state courts is associated with the need for compliance with the existing limits of the procedural freedom of arbitrators.