With 20 states now allowing the legal use of medical marijuana and the growing mainstream acceptance of the drug as a potential natural alternative for a variety of pharmaceuticals, physicians are more apt to get questions about it than ever before. Today we take a first look at a variety of legal issues and common questions around the use of medical marijuana (MMJ) by recommending physicians.

Medical media personalities as mainstream as CNN’s Dr. Sanjay Gupta have jumped into the MMJ debate with both feet, bringing the worst-kept secret in medicine much wider exposure.

From a business and patient-number standpoint the numbers are staggering for something so relatively “new” in the world of medicine. By some estimates tens of millions of Americans currently use marijuana and a surprising number classify that usage as medically related, regardless of whether it’s legal in their state or if they actually have a physician’s recommendation. Some sources estimate that medical marijuana currently generates well over $1 billion a year in revenue and that the industry could grow to six to eight times that in the next four to five years.

Here are some frequently asked questions:

Q: How many states have legalized medical marijuana usage?

A: There are currently 20 states that allow medical marijuana usage for limited medical conditions (which also vary by state). Those states currently include: Alaska, Arizona, California, Colorado, Connecticut, Washington, D.C., Delaware, Hawaii, Illinois, Maine, Massachusetts, Michigan, Montana, New Hampshire, Nevada, New Mexico, Oregon, Rhode Island, Vermont, and Washington. And that number is expected to grow. Remember, even if it’s legal in your state for medical purposes, it’s still solidly illegal under Federal law.

Q: How many doctors are currently recommending marijuana for medical purposes?

A: It’s hard to say. Many states have strict privacy laws that cover both registered, legal patients and recommending physicians. These laws were enacted, at least in part, to protect both parties from any real or perceived stigma around medical marijuana usage. Additionally, as doctors recommend for specific conditions, (the top two are PTSD and spinal injuries) there’s a thinly veiled work around.

In budding markets like Los Angeles and Denver, early adopters of medical marijuana legislation, there are countless medical practices devoted specifically to medical marijuana, which openly advertise themselves as such, in some cases even using catchy names and “Pot Doc” references. John Nicolazzo, COO of www.MarijuanaDoctors.com (a state-specific referral service for patients looking for MMJ-friendly doctors), says it’s less than 1 percent, as quoted in another recent article on the MMJ industry.

Q: How much marijuana is a patient allowed to have for medical purposes?

A: This, like many other questions about medical marijuana, is exceptionally state law specific. One of the clearest summaries of state law I found was compiled by ProCon.org, a non-profit social issue think tank. The website offers a state-by-state chart and even provides detail on statutes and legislative history in layman’s terms. In most cases the range from state to state is as low as one ounce and as “high” as 24 ounces, (hello Washington!).

Q: Where do patients get medical marijuana?

A: Again, this is a very state-law-specific question, but may states allow some combination of the following: home-growing of a specific number or usable weight of plants, the ability to buy from “caregivers,” a name given to licensed home growers who can sell directly to approved registered patients and finally, licensed retail dispensaries, a surprising number of which are owned by physicians. These operations range from stereotypical head-shop hubs decorated with posters to high-end, spa-like operations in upscale parts of the country, such as La Jolla, Calif. In most cases they have one thing in common: They are compliant, single-line pharmacies that essentially offer one product in many sizes and forms, including lozenges, liquids, edibles, and traditional “loose-leaf” varieties.

In future weeks we will continue our examination of the many business and legal issues of this growing medical industry, including liability and credentialing for recommending physicians and the issues to address when owning or operating a dispensary or marijuana-friendly practice.