This course examines markets society deems morally objectionable or politically controversial—so-called «repugnant markets»—through an economic lens. We explore how these markets emerge, the incentives that sustain them, and the often unintended consequences of efforts to regulate or ban them. Topics include the economics of crime, prohibition, discrimination, terrorism and counterterrorism, and torture. We ask: Why do individuals engage in illicit or morally questionable behavior? What are the costs and consequences of criminalization? How do bias and conflict shape economic outcomes? Can policies aimed at deterrence or control be evaluated in economic terms? Students will learn to analyze these sensitive topics with rigor and curiosity. The course encourages critical engagement with both the limits and insights of economic reasoning when applied to ethically complex domains.