Actually, it would probably be effective, but there's a more subtle connection. In the current New Republic Sherwin Nuland reviews a new book, Hysterical Men: The Hidden History of Male Nervous Illness, by Mark Micale, which chronicles just how long it took for doctors and psychiatrists to recognize that men as well as women can have depression and other severe mental or emotional disorders. Serious depression was long called hysteria, after the Greek word for womb, hystera. Properly buttoned-up (buttoned-down?) men couldn't have it. When men seemed mentally unstable other explanations were found. In most cultures of the past, proper men could not have that flighty women's disease.
The story that emerges is that cultural conditioning, except for a few exceptional thinkers, determines what most people are willing to consider as possible explanations for observed phenemona. As Nuland puts it, Micale documents "from approximately the end of the Georgian period until relatively recently, a story in which male physicians have returned to their earlier habit of bringing forth theories of female emotionality and mental frailty based on the close -- and obviously biased -- observation of women, while failing to acknowledge, or perhaps even to observe, that men of all social classes could be shown to suffer from the same ailments. Not from lack of evidence or cases to study did this situation exist, but for a complex of reasons personal and general, ranging from the anxieties of the individual male observers all the way to the growth and perpetuation of a reliable economic and civil order in nineteenth century society -- the political and cultural imperative of a patriarchal structure in which the image of stability and dependability of the rational, clear-thinking male was assured."
In other words, because of cultural/social assumptions, professional physicians couldn't see what was right in front of them, or maybe inside them.
What does this have to do with medical marijuana? Consider the only sentence then-drug-czar Barry McCaffrey ever quoted from the 1999 Institute of Medicine report on medicine and marijuana he commissioned after California passed prop. 215 in 1996: "For those reasons [cannabinoids in marijuana smoke, uncertain delivery of predictable quantities of numerous compounds] there is little future in smoked marijuana as a medically approved medication." Gen. McCaffrey ignored the fact that the report went on to say that until alternative delivery systems were developed patients should be allowed to smoke.
I contend that while there's a modicum of science in such statements, it's mostly cultural conditioning. As I discuss at some length in my book, "Waiting to Inhale," the paradigm of modern medicine includes pills (or shots) that deliver precise doses of single molecules. Within that paradigm smoking an herb seems -- well, so primitive, so shaman or medicine-man-like, so everything we scientists in white coats have moved beyond. There's value in the quest of such precision. But the test of a medicine shouldn't be whether it can be prescribed in precise doses but whether it works. The objection to smoking is far more cultural than scientific or rational.
That's my 420 contribution.