The U.S.Drug Enforcement Administration (DEA) is the agency vested with the authority to categorize and control drugs, in which process it employs a series of “schedules” ranging from the drugs most prone to abuse to to those less addictive, while factoring in legitimate medical applications for each one. Under this system, Schedule I drugs, as defined by the DEA, are drugs "with no currently accepted medical use and a high potential for abuse. Schedule I drugs are the most dangerous drugs…with potentially severe psychological or physical dependence.” Schedule II drugs are defined by the DEA as drugs “…with a high potential for abuse, less abuse potential than Schedule I drugs, with use potentially leading to severe psychological or physical dependence. These drugs are also considered dangerous.”
When attempting to determine which among the three drugs specified in the question -- MDMA (3,4-methylenedioxy-N-methylamphetimine, the basic chemical used in Ecstasy), marijuana, and heroin -- should be moved from Schedule I to Schedule II, opinions among pharmacologists, law enforcement agencies, and drug treatment specialists might vary considerably. From this educator’s perspective, the least damaging of the three, and, consequently, the one most likely to warrant being moved to Schedule II, is marijuana. While addictive, and legitimately referred to as a “gateway” drug because of the tendency for marijuana users to “graduate” to more addictive drugs, marijuana use is less addictive, and has a less pernicious social impact, than the other two being discussed. In addition, marijuana has legitimate medical applications that warrant its manufacture for such purposes under controlled circumstances.
Heroin is the easiest of the three with which to deal from a regulatory perspective. While morphine, an intermediate stage in the manufacture of heroin beginning with the cultivation of poppy plants and their natural substance, opium, certainly has legitimate medical applications (anybody recovering from surgery is a candidate for morphine injections as a painkiller), heroin is as close as a narcotic or drug can be to pure evil. It is extremely addictive, has a major and entirely negative societal impact in terms of the medical care required for a large population of addicts, the practice among many addicts of sharing needles (a leading cause of the spread of HIV), and the enormous difficulty in finding a long-term cure for addiction all vastly outweigh the minimal medicinal uses to which it can be applied.
Methadone, a synthetic substitute used to transition addicts off of heroin, is scarcely better than the heroin it was designed to replace. Which leads to the issue of regulating MDMA, as both are synethic drugs, highly addictive, and provide only marginal medical benefits, although the potential medical applications of MDMA are still be studied and could prove beneficial in treating certain mental disorders. Studies have linked prolonged use of MDMA to serious levels of depression and anxiety, and its use in the manufacture of Ecstasy has brought it into mainstream drug use, with the long-term social and health care implications that implies. While less addictive than heroin, MDMA,, can have serious and permanent effects on the brain.
The medical, social, and addictive characteristics of each of the substances listed are serious, but if one had to be moved to Schedule II, it would be marijuana, which is why some states are decriminalizing it.