Beginning in the mid-1980s, automakers began initiating voluntary recalls on a geographically limited basis when a defect or noncompliance was caused by atypical climatic conditions. For many years, these regional recalls raised no objections from D. In June 1997, D sent a letter to Ford explaining that the agency 'had concerns over several recent safety recalls conducted by Ford which were limited in terms of their geographic scope. ' D sent a letter to Chrysler and the Association of International Automobile Manufacturers as well. NHTSA (D) sent letters to some major automakers and a trade association, acknowledging that regional recalls had been authorized in the past, but stating that the agency now had 'concerns' about the practice. D then sent letters to various motor vehicle manufacturers outlining D's 'policy guidelines' for 'regional recalls.' D then sent letters to Ford and Chrysler outlining a regional recall policy. Center for Auto Safety (P) and Public Citizen, Inc. filed a lawsuit in District Court challenging the 'regulatory regime governing regional recalls established in NHTSA's 1998 letter to automakers. Ps claimed that the 1998 policy guidelines constitute a 'de facto legislative rule' that violates the Safety Act, and that, even if regional recalls are permissible in some circumstances, the policy statement violates the Administrative Procedure Act ('APA'), 5 U.S.C. 551 et seq. (2000). The District Court granted D's motion to dismiss and denied Ps' motion for summary judgment. It found that D's 1998 guidelines set out the agency's policy, not a binding rule, and thus compliance with the APA's notice-and-comment procedures was not required. Ps appealed.