BACKGROUND: Estimates are that about 300,000 people in the United States use medical marijuana. In April 2007, New Mexico became the 12th state to allow it -- joining Washington, Oregon, California, Alaska, Maine, Nevada, Vermont, Colorado, Montana, Hawaii and Rhode Island. By federal law, however, the substance is illegal.

PRO: Advocates of the drug argue it is an effective pain reliever that can work when other drugs don't. It's used by patients with a variety of ailments, including cancer, glaucoma, HIV or AIDS, multiple sclerosis and hepatitis C. Donald Abrams, M.D., the Chief of Hematology Oncology at San Francisco General Hospital and a longtime HIV researcher, says, "Marijuana has been a drug or used as a medicine for 5,000 years. It's only a short period of time that it hasn't been viewed as a medicine." He adds, "Yes, we have many more potent drugs, many more modern drugs that work for more people. But in somebody for whom those drugs don't work, if inhaling cannabis works to allow them to tolerate their chemotherapy, then that's important. No other drug that works against nausea also decreases pain." He adds it's safe, saying, "When we talk about the side effects of marijuana compared to many prescription drugs that doctors prescribe on a daily basis, it's really quite safe. The number of patients I admit to this hospital who have complications of alcohol, tobacco, heroin, cocaine, speed, even sugar, far surpasses the number of patients that I've ever admitted or ever seen where I attribute the damage to marijuana." In response to the allegation that marijuana can cause lung cancer, Dr. Abrams says a recent study shows it may actually prevent it.

A PATIENT' STORY: Brian Klein is in his late 40s and was diagnosed with both HIV and hepatitis C in 1996. His treatment for hepatitis C caused fatigue, nausea and brain fog. He tried medications to curb the nausea but was allergic to them. Others made him so sleepy he couldn't function. He then tried the FDA-approved pill version form of marijuana called Marinol but got the head buzz from it without the nausea relief. Finally, he opted to try smoking medical cannabis. Relief came within 60 seconds. Brian says, "Within a few minutes I could go eat, whereas before using it, I couldn't even keep down water. So this made a dramatic difference in my life, in my ability to be able to stay on the treatments so that I could get through it and have a successful result." He is now free of the hepatitis C virus.

CON: The U.S. Drug Enforcement Administration's position on medical marijuana, as stated on its Web site, is: "Smoked marijuana has not withstood the rigors of science -- it is not medicine and it is not safe." The DEA goes on: "The FDA noted that 'there is currently sound evidence that smoked marijuana is harmful,' and 'that no sound scientific studies supported medical use of marijuana for treatment in the United States, and no animal or human data supported the safety or efficacy of marijuana for general medical use.'" Other DEA points include:

•Marijuana use has been linked with depression, suicidal thoughts and schizophrenia

•Marijuana takes the risks of tobacco and raises them: marijuana smoke contains more than 400 chemicals and increases the risk of serious health consequences, including lung damage

•Marijuana use narrows arteries in the brain, similar to patients with high blood pressure and dementia, and may explain why memory tests are difficult for marijuana users

•Chronic consumers of cannabis can have blood flow problems in the brain, which can cause memory loss, attention deficits, and impaired learning ability

•The British Medical Association maintains marijuana "has been linked to greater risk of heart disease, lung cancer, bronchitis and emphysema"