Marijuana is illegal in because government prosecutors and politician say that marijuana is "hazordous" to ones health. Becuase that marijuana can cause sleep anxiety, paranoia, headaches, reduced blood flow to the brain, and breathing problem. Marijuana can also cause bronchitis and asthma.
But hear this. Marijuana has a healing power as well. Its a drug that muscle pains, relieves tremors, and controls the bladder for Multiple Sclerosis patients . A drug that prevents seizures in Epilepsy patients. A drug that reduces pressure within the eye for Glaucoma which can cause blindness. A drug that eases severe nausea, vomiting, and counters the appetite loses for AIDS patient.
Beside if a doctor prescribes medical marijuana then it would be in a controlled enviroment with very little given a day so the person cant use it when they want to. Also medical marijuana would be safer then street marijuana because medical marijuana would be obtained from places where marijuana would be grown pure and for medical uses therefore it wounldn't be laced with unknown narcotic like street marijuana is. This is also part of the reason why marijuana is consider so "hazordous" its tainted with other dangerious drugs.
So personally I would want marijuana to be legalized for medical purposes. Because when it comes to the health care world i would trust a physician with 11 years of medical training and internship over Know-Nothing politicians and Want-To-Be government prosecutors who think they know about medicine when their area of major is government instead of biology or chemisrty or health science like a phyisican's major would be.