WASHINGTON, D.C.: As Congress prepares to renew the debate on mandatory minimum sentencing, a new study by the RAND Drug Policy Research Center says such sentences are far less effective at reducing drug use and drug-related crime than normal law enforcement and treatment programs. The reason is the high cost of incarcerating prisoners for long periods of time. According to the study, $1 million spent on conventional law enforcement, including more arrests of drug dealers, confiscations, prosecutions and standard-length prison terms, would eliminate 70 percent more crimes against people than spending the same amount on enforcing mandatory minimums. The reason mandatory minims are so popular lies in part with the short attention span of Congressmen concerned about reelection every two years. Harsher prison sentences look tougher, and they cost less initially than expensive rehab programs that can run $1,800 per person in the first year. But long-term costs plummet: The study says that if the goverment spent the same amount over a 15-year period, mandatory minimums would reduce national cocaine consumption by 13 kilograms, while conventional enforcement would cut it by 27 kilograms. Treatment of heavy users would slash usage by more than 100 kilograms. Stiff prison sentences don't do much in the long term to deter drug trafficking because a jailed supplier is often easily replaced. High-level drug lords, who would be deterred by such tough penalties, pay someone else to carry the drugs and take the risk.