Collecting personal data is a feature of daily life. Businesses, advertisers, agencies, and law enforcement amass massive reservoirs of our personal data. This state of affairs—what I am calling the “collection imperative”—is justified in the name of efficiency, convenience, and security. The unbridled collection of personal data, meanwhile, leads to abuses. Public and private entities have disproportionate power over individuals and groups whose information they have amassed. Nowhere is that power disparity more evident than for the state’s surveillance of the indigent. Poor mothers, in particular, have vanishingly little privacy. Whether or not poor mothers receive subsidized prenatal care, the existential state of poor mothers is persist...