In the area of detection, NIJ is in the process of testing a new national data system for tracking drug use trends in the offender population. The Drug Use Forecasting system (DUF) is beginning this year in selected major cities. DUF tests urine specimens every 3 months from a new small sample of 200 arrestees. Resulting information will help the cities plan allocations for law enforcement, treatment, and prevention as well as measure the impact of efforts to reduce drug abuse and crime. It may also serve as an early warning system for drug epidemics. Regarding research on drug law enforcement, NIJ has studied a successful program in Lynn, Mass. In one neighborhood where open heroin dealing was common, a team of six narcotics officers was assigned to make the streets a risky place for heroin buyers and sellers to meet. Burglaries fell by 37 percent in the first year of the program, and robberies fell by 18 percent. The neighborhood is now free of overt drug trafficking, and there are no reports of substitute markets developing in the city.