Henrik Lando & Steven Shavell, The Advantage of Focusing Law Enforcement Effort, 24 Int’l Rev. L. & Econ. 209 (2004).
Abstract: It is shown in this paper that there may exist an intrinsic advantage in focusing law enforcement effort on a subgroup of possible violators of law, rather than applying law enforcement effort uniformly over the relevant population of potential violators. For example, it may be desirable for the tax audit rate to be higher in one region of the country than another. This may be desirable even though, as is assumed, the frequency of violations does not differ among regions.