It is being challenged in court. Constantly. Unfortunately, the Controlled Substances Act put the means of review in the hands of the DEA, which has a vested financial interest in keeping marijuana in Schedule 1 and has a tendency to do everything in its power to stall and delay the proceedings.

The first petition was filed in 1972 and was denied after 22 years of court challenges, despite the fact that the DEA's own administrative judge said it was "one of the safest therapeutically active substances known to man." Another petition was started in 1995 and denied in 2001. A third is currently in the works.

Marijuana has been proven not to cause lung cancer. Period. The largest study of its kind, funded by the US government, conducted at UCLA by a researcher who seriously expected to find a cancer link, found the reverse. See Study Finds no Cancer-marijuana link What you have to realize is that just because something contains carcinogens doesn't mean that it causes cancer. It ain't that simple. There are carcinogens in drinking water. But the government knows that marijuana doesn't cause cancer. So they just keep talking about how it has "carcinogens" and imply the cancer connection that isn't there.

Actually, marijuana does not cause lung cancer. The largest study of its kind, funded by the US government, found no link between marijuana and lung cancer, and even a tiny effect the other way.