In some cases, intelligent people implementing intelligent policies are responsible for producing a 'boomerang effect' ; they actually create more of whatever it is they seek to reduce in the first place. The boomerang effect has been achieved many times in recent years by men and women of goodwill. State legislatures around the nation have recently raised the drinking age back to 21 in an effort to reduce the prevalence of violent deaths among our young people. But such policies seem instead to have created the conditions for even more campus violence. Some college students who previously drank in bars and lounges under the watchful supervision of bouncers (夜总会、酒吧等保安人员) ( not to mention owners eager to keep their liquor licenses) now retreat to the sanctuary of their fraternity houses and apartments, where they no longer control their behaviour—or their drinking. The boomerang effect has also played a role in attempts to reduce the availability of illicit drugs. During recent years, the federal government has been quite successful in reducing the supply of street drugs. As fields are burned and contraband (违禁品) confiscated, the price of street drugs has skyrocketed to a point where cheap alternatives have begun to compete in the marketplace. Unfortunately, the cheap alternatives are even more harmful than the illicit drugs they replace. boomerang: a curved flat piece of wood that can be thrown so as to return to the thrower 回飞镖