The Wicks Group will be presenting on recently proposed amendments to the Hazardous Materials Regulations (Title 49 of the Code of Federal Regulations, parts 100-185) that impact aerosol products. As required by the Moving Ahead for Progress in the 21st Century Act (MAP-21), the Pipeline and Hazardous Materials Safety Administration (PHMSA) is proposing to amend the Hazardous Materials Regulations to adopt provisions contained in certain widely-used or long-standing special permits, including special permits pertaining to the testing of cylinders (e.g., acoustic emission and ultrasonic examination testing) and to aerosols. In relation to this agency rulemaking, The Wicks Group will also provide an overview of the regulatory context of and legal import attached to PHMSA letters of interpretation in order to guide compliance with the Hazardous Materials Regulations and, if necessary, to challenge improper enforcement actions.