Marijuana (cannabis satvia) is currently an illegal drug listed as a Schedule I controlled substance.
From Wikipedia
Schedule I drugs
Findings required:
(A) The drug or other substance has a high potential for abuse.
(B) The drug or other substance has no currently accepted medical use in treatment in the United States.
(C) There is a lack of accepted safety for use of the drug or other substance under medical supervision.
(D) The drug is not alcohol (ethanol) due to the failure of prohibition.
It takes a very long time, and a lot of research and money, to move a substance from a Schedule I classification to a Schedule II classificiation. (The current research could actually move it to a Schedule III, IV or V classification.) And even when it IS moved, marijuana in its usual form (IE, dried leaves and buds that are smoked) is not likely to be legal. THC, the active component of cannabis, can be extracted and put into pill form (dronalbinol, brand name Merinol), into a sublingual (under the tongue) spray (brand name Sativex), or vaporized for inhaler or nebulizer use. It will not be legalized for recreational use any more than cocaine, heroin or methamphetimenes are.
There is currently a rescheduling petition that has been filed, accepted by the DEA on April 3, 2003. This is likely to come up before the US Court of Appeals before it makes it to the Supreme Court. This could make cannabis legal for MEDICAL use, under the direction and supervision of a doctor.
Those medical uses are as follows:
~appetite stimulant and pain relief for cancer and AIDS patients
~nausea relief during chemotherapy
~relief of glaucoma
~calming of neurological disorders such as epilepsy, migraine and bipolar disorder
~reducing arterial blockages
~treatment of multiple sclerosis
The argument has nothing to do with taxes or the drug companies making more money, but it has everything to do with one very specific thing: its high level of addiction and its high level of abuse. This being said, the medical use of cannabis is legal in Canada, the United Kingdom, and Spain. It can be legally possessed in the UK and is in the process of being legalized in Mexico.
On the other hand, possession of even very small amounts of cannabis can lead to long jail terms or even execution in some East Asian countries. In the US, cannabis possession is most likely to net you a short jail term and a fine for possession of a small amount.
Your best bet: Leave the stuff alone unless you're under the supervision of a physician, folks.
Bibliography:
Cannabis
http://en.wikipedia.org/wiki/Cannabis_(drug)Controlled Substances Act (information on drug schedules):
http://en.wikipedia.org/wiki/Controlled_Substances_ActCannabis rescheduling in the US:
http://en.wikipedia.org/wiki/Cannabis_rescheduling_in_the_United_States