EPA has finalized a regulation you can live with, but someone
dissatisfied with that result has sued the Agency. Should you
intervene to defend EPA's action? Is it worth it? Does the
court really pay attention to the arguments of an intervenor? A
recent decision by the D.C. Circuit in Masias v. EPA, No. 16-1314
(D.C. Cir. Oct. 19, 2018), illustrates the value of participation
as a Respondent-Intervenor in these circumstances.
Masias involved several consolidated challenges to EPA's
designation of specific areas as "unclassifiable" for
EPA's primary National Ambient Air Quality Standard for sulfur
dioxide. EPA promulgates ambient standards to protect public health
pursuant to the federal Clean Air Act. After an ambient standard is
promulgated, the Act requires EPA to designate all areas of the
country as "attainment" or "nonattainment" for
that standard. If EPA cannot determine whether a particular area
meets an ambient standard based on the information before
