Beveridge & Diamond

Clean Air Act Conformity Alert

Beveridge & Diamond, P.C., October 24, 2006

On October 20, 2006, the D.C. Circuit court decided a challenge brought by Environmental Defense ("ED") and others to EPA's transitional transportation conformity rules, which had been promulgated in 2004.  Environmental Defense v. EPA, No. 04-1291 (D.C. Cir. 2006); Transportation Conformity Rule Amendments, 69 Fed. Reg. 40,004 (July 1, 2004).  The decision was a mixed result consisting of three parts.

First, the court rejected ED's challenge to EPA's "milestone" rules at 40 C.F.R. 93.118(b), (d) and (e)(6).  These rules originated in prior EPA rulemakings in 1993 and 1997, and were the subject of litigation in Atlanta in the early 2000s.  The court found that the rules had not changed substantially in the 2004 rulemaking, and that ED should have challenged them in 1993 or 1997 if at all, but that it was too late now to re-open the rulemaking process.  

Second, the court invalidated EPA's 2004 "interim budget test" option at 40 C.F.R. 93.109(e)(2)(v).  This test was designed "to provide MPOs [Metropolitan Planning Organizations] with an interim test to take the place of current SIPs (based on one-hour NAAQS) until the new SIPs (based on eight-hour NAAQS) are approved."  Although the court recognized (as EPA argued) that the interim test could actually be more stringent than a SIP Motor Vehicle Emissions Budget ("MVEB") test and would be a "sound means" to transition from the 1-hour to 8-hour standard, the court found that the Clean Air Act simply did not allow for any test other than the MVEB budget test.  The court took pains to point out that "current SIPs [including outdated 1-hour SIPs] are legally sufficient until they are replaced by new SIPs."   

Third, on a related issue, the court rejected a challenge to EPA's build/no build tests at 40 C.F.R. 93.119(b)(2), (d) and (e).  The challenge was limited to application of the build/no build test to marginal and below ozone non-attainment areas, as well as coarse (PM10) and fine (PM2.5) particulate matter non-attainment areas, without MVEBs.  The challengers argued that all transportation plans must show reductions in emissions in order to support the Clean Air Act's goals of reducing violations and expeditious attainment of NAAQS.  The court disagreed, finding that the SIP as a whole must reduce emissions, but that "conformity to a SIP can be demonstrated by using the build/no build test, even if individual transportation plans do not actively reduce emissions," as long as the transportation plan "avoids increases" in emissions.  

Despite some internal inconsistencies, the practical consequences of the decision are clear.  The ruling invalidates the interim build/no build test for areas that have older MVEBs in pre-existing 1-hour SIPs, thus possibly creating consequences for areas that need to establish new, workable MVEBs.  In areas without MVEBs or existing SIPs (for example, in newly-created non-attainment areas), consistent with existing practice, the build/no build test can still be used.  Most importantly, the ruling clarifies that NAAQS attainment is a function of the overall SIP, and transportation plans will not have to "actively reduce" mobile source emissions as long as emissions hold steady or fit within mobile source budgets.  EPA will likely issue interpretative guidance in the next few months on this decision.  

For more information, contact David Friedland at (202) 789-6047,, or Max Williamson at (202) 789-6084,