P is an association of about 200 Illinois nursing homes participating in the Medicare program. Medicare Part A provides payment to nursing homes that provide care to Medicare beneficiaries after a stay in hospital. A home must enter into a provider agreement with D, and it must comply with numerous statutory and regulatory requirements. Inspectors report violations, called 'deficiencies.' And 'deficiencies' lead to the imposition of sanctions or 'remedies.' The regulations focus on the imposition of sanctions or remedies. The remedial regulations (and a related manual) in effect tell Medicare-administering agencies how to impose remedies after inspectors find that a nursing home has violated substantive standards. The statute and regulations also create various review procedures. P using federal-question jurisdiction filed a complaint that attacked the regulations as unlawful. In its view: (1) certain terms, e.g., 'substantial compliance' and 'minimal harm,' are unconstitutionally vague; (2) the regulations and manual, particularly as implemented, violate statutory requirements seeking enforcement consistency, 42 U.S.C. § 1395i-3(g)(2)(D), and exceed the legislative mandate of the Medicare Act; (3) the regulations create administrative procedures inconsistent with the Federal Constitution's Due Process Clause; and (4) the manual and other agency publications create legislative rules that were not promulgated consistent with the Administrative Procedure Act's demands for 'notice and comment' and a statement of 'basis and purpose,' 5 U.S.C. § 553. Under 28 U.S.C. § 1331 'district courts shall have original jurisdiction of all civil actions arising under the Constitution, laws, or treaties of the United States.' There is also a special Medicare review route that P elected not to follow. Title 42 U.S.C. § 1395ii makes § 405(h) applicable to the Medicare Act 'to the same extent as' it applies to the Social Security Act. Section 405(h) purports to make exclusive the judicial review method set forth in § 405(g). The District Court dismissed the complaint for lack of federal-question jurisdiction. The Court of Appeals reversed. The Supreme Court granted certiorari.