Association of Irritated Residents v. United States Environmental Protection Agency, 686 F.3d 668

Association petitioners challenge EPA's final action approving in part and disapproving in part California's SIP revisions for South Coast ozone under the Clean Air Act.
EPA previously approved the 1997/1999 SIP and later partial approvals/withdrawals culminated in the 2003 SIP Revision (Attainment Plan, PEST-1, and a no-Transportation-Control-Measures assertion).
EPA proposed to approve the non-withdrawn elements of 2003 Attainment Plan but disapprove the attainment demonstration and MVEBs; EPA then finalized such partial disapproval in 2009.
Petitioners argue (1) EPA failed to order a revised attainment plan after disapproval, (2) EPA erred by approving PEST-1 which lacked enforceable commitments, (3) EPA failed to require TCMs to offset growth in vehicle miles traveled, and (4) EPA failed to ensure the SIP is adequate or trigger FIP/SIP-call mechanisms.
Court grants petition, remands for further proceedings to require revised attainment plan, to evaluate PEST-1 enforceability, and to address TCMs and SIP adequacy.
Key statutory context includes SIP approvals/disapprovals, FIP/SIP-call triggers, and MVEB conformity requirements.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Did EPA arbitrarily fail to evaluate SIP adequacy after 2003 revisions?	Petitioners: EPA had to assess whether the existing SIP remained adequate.	EPA argued partial disapproval did not compel further action.	Yes; EPA's failure to evaluate the existing SIP was arbitrary and capricious.
Was EPA's approval of PEST-1 arbitrary and capricious?	PEST-1 lacked enforceable commitments under the Act.	EPA relied on Wells Memorandum as enforceable commitments.	Yes; EPA acted arbitrarily in approving PEST-1.
Did EPA err by not requiring transportation control measures to offset VMT growth?	TCMs were required to offset growth in emissions from VMT per §7511a(d)(1)(A).	Aggregate emissions would decline anyway; no TCMS needed.	Yes; statutory text requires consideration of growth in emissions from VMT, not just aggregate emissions.
Did EPA have a duty to act (FIP or SIP call) in response to partial disapproval?	EPA had to promulgate a FIP or initiate a SIP call due to inadequacies.	Discretion limited the need for FIP if existing SIP could suffice.	Yes; EPA had an affirmative duty to take further action consistent with the Act.

Hall v. U.S. EPA, 273 F.3d 1146 (9th Cir. 2001) (EPA must evaluate the whole plan as revised to meet attainment requirements)
Train v. Natural Res. Def. Council, 421 U.S. 60 (U.S. Supreme Court 1975) (statutory interpretation and agency duty under Clean Air Act)
Barnhart v. Sigmon Coal Co., 534 U.S. 438 (2002) (ordinary tools of statutory construction; deliberate disregard of language)
Hall v. U.S. EPA, 273 F.3d 1146 (9th Cir. 2001) (reiterated need to assess plan adequacy with revisions)
Sierra Club v. Johnson, 541 F.3d 1257 (11th Cir. 2008) (agency discretion in finding SIP inadequacy)
Citizens Against Ruining the Env’t v. EPA, 535 F.3d 670 (7th Cir. 2008) (limitations on agency discretion in SIP adequacy findings)
United States v. Wenner, 351 F.3d 969 (9th Cir. 2003) (statutory interpretation guiding baseline/emission calculations)
Motor Vehicle Mfrs. Ass’n of U.S. v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29 (U.S. Supreme Court 1983) (arbitrary and capricious review standard)
1000 Friends of Maryland v. Browner, 265 F.3d 216 (4th Cir. 2001) (modeling inadequacy and review standards)
Warmerdam v. Earlimart, 539 F.3d 1062 (9th Cir. 2008) (Wells Memorandum not part of SIP; enforceable commitments issue)