Corrective policies attack perceived crime causes to reduce the number of criminals through measures such as employment programs, rehabilitation, or youth recreation activities. Mechanical programs largely carried out by law enforcement authorities reduce criminal activities by methods which produce high clearance rates, increased punishment, or reduced crime opportunities. According to Reppetto, each involves possible displacement. This paper focuses on determining the optimal level of crime prevention resources allocated through these two policy instruments in a bijurisdictional system where spillover exists. The paper concentrates on three situations: a simple model of territorial spillovers using two neighboring communities where each has a two dimensional crime prevention policy; two identical adjacent communities where the model analyzes crime prevention policies of each community and the policy of a central authority; and an intertemporal framework for one community. Economic intuition implies that in a centralized system, activities generating positive external economies should be increased, while activities generating external diseconomies should be reduced. The model presented in this paper indicates that this is one possible outcome, but in some cases, the centralized solution involves either more or less of both corrective and mechanical measures. The outcome depends on the interrelation of the two policies in reducing crime, on the amount of externalities they generate, and on their effectiveness. Thus, both positive and negative externalities require a coordinated mix of public actions, and the structure of law enforcement governance should be broad in both spatial and temporal dimensions. Graph, formulas, 8 footnotes, and 20 references are supplied. (Author abstract modified)