Only 'legislative rules' have the force and effect of law. See Chrysler Corp. v. Brown, 441 U.S. 281, 302-03 & n.31 (1979). A 'legislative rule' is one the agency has duly promulgated in compliance with the procedures laid down in the statute or in the Administrative Procedure Act. Courts have also recognized that an agency's other pronouncements can, as a practical matter, have a binding effect. See, e.g., McLouth Steel Prods. Corp. v. Thomas, 838 F.2d 1317, 1321 (D.C. Cir. 1988). If an agency acts as if a document issued at headquarters is controlling in the field, if it treats the document in the same manner as it treats a legislative rule, if it bases enforcement actions on the policies or interpretations formulated in the document, if it leads private parties or State permitting authorities to believe that it will declare permits invalid unless they comply with the terms of the document, then the agency's document is for all practical purposes 'binding.' See Robert A. Anthony, Interpretative Rules, Policy Statements, Guidances, Manuals, and the Like--Should Federal Agencies Use Them to Bind the Public?, 41 Duke L.J. 1311, 1328-29 (1992), and cases there cited.
Under ...