This case study focuses on the phenomenon of pens’ blackout in Brazil where efforts to reduce corruption and increase the authority of control bodies have caused civil servants to avoid taking decisions for fear of being penalised. The case can be used to teach concepts such as how laws and control institutions can backfire by deterring honest civil servants; the role of legal uncertainty and audit; the relationship between executive and control authorities; and how to protect and promote discretion and innovation in the public service.