Local-level enforcement has been cited as an effective drug enforcemen
t strategy by some policy makers and experts. A more intensive tactic,
with focus on a specific target area and referred to as ''crackdowns'
', has been implemented in some cities. In this paper, we analyze a ma
thematical model due to Caulkins, to study the effect of focussed enfo
rcement on drug markets. Specifically, we consider both fixed and dyna
mic enforcement policies. Our analysis suggests that drug dealing can
be effectively controlled only if enforcement resources exceed a certa
in threshold level, and that the success of a crackdown operation may
be lost fairly quickly if care is not taken to prevent the market from
returning. This should provide enforcement officials with analyticall
y derived ''rules of thumb'' to help make improved policy decisions.