The concept of reasonableness pervades constitutional doctrine. The concept has long served to structure common law doctrines from negligence to criminal law, but its rise in constitutional law is more recent and diverse. This Article aims to unpack surprisingly different formulations of what the term reasonable means in constitutional doctrine, which actors it applies to, and how it is used. First, the underlying concept of reasonableness that courts adopt varies, with judges using competing objective, subjective, utility-based or custom-based standards. For some rights, courts incorporate more than one usage at the same time. Second, the objects of the reasonableness standard vary, assessed from the perspective of judges, officials, legislators, or citizens, and from the perspective of individual decision-makers or general institutional or government perspectives. Third, judges may variously apply a constitutional reasonableness standard to a right, to the assertion of defenses, waivers, or limitations on obtaining a remedy for the violation of a right, or to standards of review. The use of the common term "reasonableness” to such different purposes can blur distinctions between each of these three categories of standards. The flexibility and malleability of reasonableness may account for its ubiquity and utility. Entire constitutional standards can - and have - shifted their meaning entirely as judges shift from one concept or usage of reasonableness while appearing not to change the “reasonableness” standard or to depart from precedent. That ambiguity across multiple dimensions explains both the attraction and the danger of constitutional reasonableness. In this Article, I point the way to an alternative: regulatory constitutional reasonableness, in which reasonableness is presumptively informed by objective and empirically-informed standards of care, rather than a set of shape-shifting inquiries.
Brandon L. Garrett, Constitutional Reasonableness, 102 Minnesota Law Review 61-126 (2017)