The traditional military model of police authority arose as a result the 19th century English Police structure, the need for discipline, the organization and rank structure of police departments, and the authority-based values of officers. The discretionary model rests on the assumption that the official at the scene is best able to judge necessary action and that professionalism is a function of the autonomy and discretion allowed to members. Under the military model, performance is measured in terms of adherence to rules and policy, while the discretionary model defines success in terms of minimum intrusion and coercion. The letter-of-the law mentality can lead to an over-reliance on rules and may negate any skills, talents, or experience the officer brings to the scene. Worse, the rules may become an end in themselves. While departments must provide guidelines and training in the appropriate exercise of discretion, the competence and talents of police professionals also should be recognized. An integration of the two approaches is recommended. 8 footnotes.