In a growing number of consumer transactions today, firms exploit consumer confusion and promote poor buying choices. The resulting transactions are often lousy, whether one uses autonomy, welfare, or fairness as the metric. Disclosure and product-design'rules, both of which focus on the actions of firms, have failed to solve this problem. While regulators seem intent on doubling down on disclosure, firms' ability to frame consumer reception of mandated disclosures ultimately hamstrings this project. Regulation of transaction terms can be impotent as well, because firms often reformulate products to evade prescriptive design rules. Moreover, the speed with which firms foil disclosure and design regulation will only increase in the device-mediated world of big data. Consumer law-limited institutionally to slow, circumscribed responses-trails behind firms. The time is ripe for a fresh approach. In other areas, most notably environmental regulation, prescriptive regulation has been supplemented with performancebased regulation monitored through ongoing field-testing. Rather than the law dictating that a factory smokestack must incorporate a particular scrubber, the law sets limits on a firm's emissions and the firm can then determine how to meet those limits. By uniting the goals of the firm with the goals of the regulator, the regulator is able to harness the firm's innovation in finding ways to meet those goals. By continually monitoring the outcome of interest, regulators obtain systematic information that they can use both to stop problems before substantial harm is done and to make regulation more effective. Performancebased regulation is thus more functional and more adaptive than prescriptive regulation.

Two ways in which we might apply this regulatory paradigm to consumer transactions are comprehension standards and suitability standards. Consumer-comprehension standards that firms could meet by whatever means they see fit are an intuitive move from disclosure mandates. Field-testing of each