AASHTO-AMPO Amicus Brief Re: Sierra Club v EPA , Case 15-1123

In support of the 4/23/2018 EPA re-hearing request, AASHTO-AMPO submitted the attached Amicus Brief to the U.S. Court of Appeals for the D.C. Circuit on 4/30/2018. The Brief discloses the disruptive consequences to State DOTs and MPOs. It discloses the practical and legal implications of the decision that were not fully addressed in EPA’s rehearing request.


  • The Court erred in finding that “Anti-Backsliding Requirements” compel EPA to retain transportation conformity for a revoked NAAQS. The court’s decision ignores the plain language of Section 42 U.S.C. § 7502(e) that limits the need for anti-backsliding requirements only when a standard is relaxed.
  • The Court erred in finding that conformity determinations are required in orphan areas for a revoked NAAQS.
  • The Court should remand without vacatur to avoid re-imposing conformity for areas that attained the 2008 NAAQS.

Requested Remedies:

  • Modify decision or have supplemental briefing.

Transportation Background: The court decision re-applies transportation conformity and maintenance requirements for the rescinded 1997 ozone NAAQS. Other implications are under review.  82 areas throughout the U.S. met both the 1997 ozone NAAQS and the more stringent 2008 ozone NAAQS. The court designated these “orphan areas.” Beaumont-Port Author is the only Texas orphan area. 40-50 areas were nonattainment or maintenance for the 1997 ozone NAAQS and nonattainment for 2008 ozone NAAQS.

Motion for Amicus Brief by AASHTO and AMPO and Proposed Brief

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