is not a prerequisite to Chevron/Auer deference, informal statements of agency interpretation are not entitled to Chevron/Auer deference. High Chevron/Auer deference requires some level of consistency by the agency. An agency can lose Chevron/Auer deference in a specific case if its adjudicatory procedures in that case were haphazard. Chevron/Auer only applies to an agency's interpretations of a statute or rule reached on its own reasoned decisionmaking, not to interpretations of Congressional intent or case law, which are the purview of the judicial branch. Congress may specify procedures that an agency must use in its gap-filling—a delegation of authority to make "rules" invokes the § 553 defaults for procedure, while a charge to promulgate "regulations" implicates legislative procedure. "Interpretative" rules and "shortcut procedure" exemption of § 553(b) An "interpretative" rule sets out the agency's interpretation of a statute or rule, without altering rights or obligations. If the interpretation fails at least one of the Chevron/Auer criteria, then the interpretation falls into the category of "interpretative rule" which binds only the agency itself, and is entitled to at most Skidmore deference. Availability of the § 553(b) "interpretative" exemption The line for permissible exercise of the § 553(b) "interpretative" exemption is blurry—courts and treatise writers uniformly complain about this. The most basic requirement for the "interpretative" exemption is that the agency "interpret" a validly promulgated law (statute or regulation), by following a recognizable interpretative path originally set out by the statute or regulation. An agency may promulgate an "interpretative" rule "only if the agency's position can be characterized as an 'interpretation' of a statute or legislative regulation rather than as an exercise of independent policymaking authority." Mere "consistency" (in the sense of "absence of clash") is insufficient. Most "gap filling" is beyond the scope of *interpretative" authority. A valid interpretative rule merely explains, but does not add to or alter, the law that already exists in the form of a statute or legislative rule. An "interpretative" rule cannot create a new requirement, carve-out, or exception from whole cloth. If the rule changes "individual rights and obligations" (rather than resolving ambiguity), the rule requires legislative procedure. An agency may promulgate interpretative rules outside the scope of its rule making authority. Where an agency can only issue legislative rules pursuant to an express grant of authority from Congress, an agency may (and is encouraged to) issue advisory interpretations to guide the public. If an agency