Geo Group, Inc. v. Menocal · ¶29

That reasoning describes a defense, not an immunity. Yearsley provides protection to a contractor when it has received a lawful authorization and acted according to its terms—meaning, when the contractor has acted within legal bounds. So in invoking Yearsley, the contractor is making the argument of a merits defense—that it is not liable because it has complied with the law. See supra, at 445. Conversely, Yearsley's protection runs out when the contractor may have violated the law—when the contractor either acted under an illegal authorization or exceeded the scope of a legal one. By drawing the line there, Yearsley ensures that it will never shield unlawful conduct, in the way that all immunities do. See supra, at 445. In short, because Year sley protects a contractor only when—and only because—it has acted lawfully, Yearsley operates as a defense to liability on the merits. And that…

preliminary print (page proof)
Source edition
Passage preview. Read in context for the complete text, notes and references.