Document ID: ./input/supremecourt_opinions/opinions/boundvolumes/529bv.pdf
Page Number: 431

529US2

Unit: $U45

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NORFOLK SOUTHERN R. CO. v. SHANKLIN

Opinion of the Court

This construction, however, contradicts the regulation’s
plain text. Sections 646.214(b)(3) and (4) make no distinc-
tion between devices installed for “minimum protection” and
those installed under a so-called “priority” or “hazard” pro-
gram. Nor does their applicability depend on any individu-
alized determination of adequacy by a diagnostic team or an
FHWA ofﬁcial. Rather, as the FHWA itself explained in its
Easterwood brief, §§ 646.214(b)(3) and (4) have a “compre-
hensive scope.” Brief for United States in CSX Transp.,
Inc. v. Easterwood, O. T. 1992, Nos. 91–790 and 91–1206, at
12. Section 646.214(b)(3) states that its requirements apply
to “any project where Federal-aid funds participate in the
installation of the devices.” 23 CFR § 646.214(b)(3)(i) (1999)
(emphasis added). And § 646.214(b)(4) applies to all feder-
ally funded crossings that do not meet the criteria speciﬁed
in (b)(3). Either way, the federal standard for adequacy
applies to the crossing improvement and “substantially
subsume[s] the subject matter of the relevant state law.”
Easterwood, 507 U. S., at 664.

Thus, contrary to the Government’s position here,
§§ 646.214(b)(3) and (4) “specify warning devices that must
be installed” as a part of all federally funded crossing im-
provements.
Id., at 666. Although generally “an agency’s
construction of its own regulations is entitled to substantial
deference,” Lyng v. Payne, 476 U. S. 926, 939 (1986), no such
deference is appropriate here. Not only is the FHWA’s in-
terpretation inconsistent with the text of §§ 646.214(b)(3) and
(4), see Robertson v. Methow Valley Citizens Council, 490
U. S. 332, 359 (1989), but it also contradicts the agency’s own
previous construction that this Court adopted as authorita-
tive in Easterwood, cf. Maislin Industries, U. S., Inc. v. Pri-
mary Steel, Inc., 497 U. S. 116, 131 (1990) (“Once we have
determined a statute’s clear meaning, we adhere to that de-
termination under the doctrine of stare decisis, and we judge
an agency’s later interpretation of the statute against our
prior determination of the statute’s meaning”).