New York City’s A1C Registry is a paradigm of “emergent” public health surveillance: It subjects a population with a non-communicable, non-exposure-related health condition to individualized, ongoing, and intimate government surveillance. In so doing, it employs a surveillance model that was developed in the context of serious contagious disease and was justified in part by the efficacy of government interventions to prevent contagious disease from spreading. This justification for the surveillance model does not apply to the principal present-day threats to public health: obesity and other chronic conditions like diabetes. In addition, emergent public health surveillance mimics three features of law enforcement and national security surveillance that courts and commentators have found both troubling and relevant to the scope of privacy protections afforded under the Fourth Amendment. Like security programs, emergent public health surveillance involves comprehensive, intimate and individualized surveillance, employs electronic data collection systems which have a low marginal cost and to which data mining techniques are easily applied, and scrutinizes politically vulnerable domestic populations. Building in part on Fourth Amendment challenges to, and critical commentary about, security surveillance programs, this Note argues that emergent public health surveillance programs intrude upon a fundamental privacy interest. Accordingly, they should receive strict scrutiny under the Fourteenth Amendment. The constitutional inquiry should turn in part upon the efficacy of the public health intervention enabled by the challenged surveillance program.