In Noel Canning v. NLRB, 705 F.3d 490 (D.C. Cir. 2013), the D.C. Circuit held (inter alia) that the President’s constitutional power to make recess appointments does not include recesses during a session of the Senate (“intrasession recesses”), as opposed to recesses between sessions (“intersession recesses”). Many commentators have taken Canning to be principally a textualist and originalist decision. I argue, to the contrary, that Canning’s textualism and originalism are derivative strategies by which the court attempted to fashion a precautionary rule against presidential aggrandizement. As such Canning is best understood to exemplify a mode of constitutional adjudication that we might call precautionary constitutionalism. As a normative matter, Canning illustrates the major problem of precautionary constitutionalism: myopic focus on a target risk may cause the rulemaker to ignore or underestimate countervailing risks, resulting in unintended, counterproductive or perverse consequences.