In a letter this month to inquiring lawmakers, the Drug Enforcement Administration quietly announced that it will decide whether to change the federal status of marijuana "in the first half of 2016." The move excited legalization advocates and reminded everyone else of how convoluted our drug regulatory process can be.
Under the Controlled Substances Act , enacted in 1970 while facing backlash against the recreational drug use of the 1960s, the federal government categorizes drugs based on their medical value and potential for abuse. If substances have no potential for abuse, they aren't controlled at all. If they do, they're classified in one of five schedules of decreasing severity.
Drugs in Schedule I are deemed as having "no current accepted medical use" and a high potential for abuse -- the category where marijuana resides, alongside heroin, LSD, ecstasy and others. These drugs are regulated with extreme stringency in terms of access, research and supply.