Contemporary legal philosophers commonly understand the normative force of law in terms of practical reason. They sharply disagree, however, on how exactly it translates into practical reason. Notably, some have argued that the directives of an authority that meets certain prerequisites of legitimacy generate reasons for action that exclude some otherwise applicable reasons, while others have insisted that such directives can only give rise to reasons that compete with opposing ones in terms of their weight (an approach I will call the weighing model). Does the weighing model provide a normative framework within which law could adequately facilitate correct decision-making? At first glance, the answer appears to be ‘yes’: there seems to be nothing about law-following values—such as coordination reasons, the desirability of social order, deferential expertise, etc.—which prevents them from being factored into our decision-making in terms of normative weight that tips the balance in favor of compliance with law inasmuch as it is worthwhile to comply with it. This impression, however, turns out to be incorrect when, drawing on a body of empirical work in psychology, I observe that many of the practical difficulties law typically addresses are difficulties that have part of their root in biases to which we are systematically susceptible in the settings of our daily activity. I argue that the frequent presence of those biases in contexts of activity which law regulates, and the pivotal role law has in counteracting them, emphatically militate against the weighing model and call for its rejection.