As practice under Section 337 has grown, so has interpretation of the law. Many precepts once taken for granted have been overruled and others have arisen that will survive until challenged in the future. This guide provides an introduction to practice under Section 337 before the U. S. International Trade Commission for those who are not familiar with it, or for those who want a quick update. The guide will provide the reader with a better understanding of what to expect when filing a complaint or in being named as a respondent in a Section 337 investigation. This updated guide provides analysis and explanation of the participants in Section 337 investigations and discusses the unique role played by the ITC. It also focuses on the procedural rules of a Section 337 investigation, including preparation of a complaint, the discovery process and other pre-hearing procedures, the hearing and post-hearing processes and the remedies available to a successful complainant. Other topics addressed include enforcement of a violation ruling, parallel litigation and appellate court review of an ITC decision.