This article uses the concepts of McDonaldization of society and the performance paradox to consider critically the public performance management reforms driven by the ideology of New Public Management in the past two decades and more. It focusses on the aftermath of the application of business-like performance management to the Taiwan government’s law enforcement agencies in order to highlight the dilemma of the application of performance management techniques to the public sector. Through the case study of the police agency in Taiwan which has been implementing performance management for a long time, this article shows how the behaviour of a government agency responsible for maintaining social order has been distorted as a result of the performance management reforms. Though government leaders have identified the problem, it has already been deeply embedded in the police agency and become part of its culture, hence it is difficult to overcome the problem now. This case study should be a good reference for those countries which have just introduced performance management to law enforcement agencies.