On June 28, 2014, the United States District Court for the District of Columbia held that the Clean Air Act (CAA) does not impose a nondiscretionary duty on the EPA to regulate emissions from animal feeding operations (AFOs) or to designate AFOs as emissions sources. Zook v. EPA, No. 13-1315 (D.D.C. June 30, 2014). The district court’s ruling reaffirms the significant deference given to an agency when it makes policy judgments pursuant to its controlling statute — in this case, the CAA.  The explicit language in CAA Sections 108 and 111 demonstrates that Congress assigned judgment and policymaking discretion to the EPA rather than to the courts.  However, the scenario in Zook also underscores the significant pressure on the EPA to increase regulation of AFOs.