How to identify reversible charge error

The issue in United States v. CITGO was whether an “equalization tank” — a holding tank that plays a role in the process for handling oil refinery wastewater — is an “oil-water separator” within the meaning of the regulations implementing the Clean Water Act.  The jury instructions quoted the regulation’s definition of an oil-water separator and then added: “[t]he definition of oil-water separator does not require that [it] have any or all of the ancillary equipment mentioned such as forebays, weirs, grit chambers, and sludge hoppers . . . . An oil-water separator is defined by how it is used.” The Fifth Circuit found an abuse of discretion in that additional sentence and reversed CITGO’s convictions: “This purely functional explanation is not what [the regulation] says, however: it defines an oil-water separator by how it is used and by its constituent parts. . . .  Although the jury was also provided the exact text of Subpart QQQ, the court’s instruction told them what it means and thus undoubtedly affected the verdict. For this harmful error, the Clean Air Act convictions must be reversed.”  No. 14-40128 (Sept. 4, 2015).