Most environmental practitioners focus on the end-life of hazardous materials. But before a hazardous substance is disposed of, recycled, or becomes the subject of a remedial action, many of these hazardous materials are transported across the United States in commerce. Those persons who offer such hazardous materials for transportation are stringently regulated by the U.S. Department of Transportation (DOT) under the federal Hazardous Materials Transportation Law, 49 U.S.C. 51010 et seq., and the DOT’s implementing regulations (HMR), 49 C.F.R. parts 171–185. Provided that an offeror complies with pre-transportation requirements under the HMR, an offeror is generally liable for noncompliance that occurs during shipment only if the offeror “should have known” that a violation would occur. A relatively recent DOT decision in In the Matter of Lighthouse Environmental Services, Inc., however, signals a possible broadening of that standard. The decision demonstrates that an offeror may be responsible for anticipating the improper acts of third parties during the shipment of hazardous materials and liable under the HMR if the offeror does not take steps pre-transport to prevent such noncompliance.