犯罪是一種社會偏差行為，造成社會不安及經濟損失。很多研究者指出，經濟因素是犯罪的重要考量之一。警察的功能在控制犯罪。然而，法律由警察來執行，而警察是人，也可能犯錯。因此，警察的偏差行為，也必須設法防範。本文討論廣義的監察問題。在政治及商業的範疇，都有監察的必要，以確保人人遵守規範。本文提出一個簡單的模型，並藉由此一模型，描畫一個政治體系的可能的演進過程。從政者及民意代表，可以被看成人民的警衛，保護人民辛苦工作的成果。不過，警衛也可能會犯錯，因此可能必須再雇用額外的警衛，來看管原有的警衛。在理性的雇用原則之下，警衛人數和個別警衛的保護的效率成負相關。此一關係對政治體系的演進，可能有若干啟示，此一結果也可以應用在台灣國會改革，立法委員人數減半的議題上。

Crime is a deviation from social norms, causing societal disorder and economic loss. Many researchers have pointed out that economic factors constitute a critical element in the decision on committing a crime. The police are supposed to control crimes. To be sure, the law is enforced by human beings, subject to similar potential deviation. Consequently, the deviant behaviors of law enforcement must also be addressed. This paper explores the general issue of monitoring, in addition to enforcement. Similar monitoring concerns exist in the political arena and the business environment. A simple model based on monitoring concerns is proposed and used to delineate a possible evolutionary path of the political system. Politicians and representatives can be considered as guards hired by the people to protect the fruits of their hard work. However, worries about the guards’ misdemeanor may necessitate further deployment. Under rational guard hiring, the negative relationship between the effectiveness and the number of guards may shed light on the evolution of the political system. The result is applied to analyze a proposal on cutting the size of the legislature in Taiwan.