After the inauguration, the Drug Enforcement Administration (DEA) continued to carry out such raids, despite Obama's promise. Holder was asked if those raids represented American policy going forward.

"No," he said. "What the president said during the campaign, you'll be surprised to know, will be consistent with what we'll be doing in law enforcement. He was my boss during the campaign. He is formally and technically and by law my boss now. What he said during the campaign is now American policy."

The exchange takes place at about the 25:00 mark here.

Holder's declaration is a high point for the movement to legalize medical marijuana, which has been growing for decades despite federal hostility.

"It's good news for people in California who are so ill that they have gotten a doctor's note in compliance with the law," said Sen. Barbara Boxer (D-Calif.) when told of Holder's promise. "If you have a doctor's note, you should be able to get whatever medicine you need."

Sen. Dianne Feinstein (D-Calif.) was not as quick with approval. "I've got to think about that a little bit," she said. Feinstein was mayor of San Francisco when in the '70s and '80s when the issue was first being debated.

In 2007, for a book on drug culture and drug trends, This Is Your Country On Drugs, that will be released in June, I toured a number of the medical marijuana dispensaries in question and interviewed their owners and customers. This is what I found, excerpted from the book:

A first-time visitor to Harborside Health Center might have a hard time believing he's about to enter "an extraordinary environment of medical care, honesty, and friendliness," as the place describes itself online. Situated in a nondescript warehouse just off the freeway in Oakland, California, it's labeled only with the giant digits of its street number, 1840. Two security guards in blue are posted outside, and the facility is also equipped with motion detectors, video and audio surveillance, and laser alarms. The guards are, in fact, extraordinarily friendly, offering professional smiles to those who approach. But they're not exactly welcoming, and for good reason: at Harborside, no one gets in without a medical-cannabis card or a recommendation from a doctor.

I had come with a federal medical researcher who'd recently finished a long study of medical-cannabis clubs in the Bay Area and was able to vouch for me. But it's not exactly impossible to get a card or a recommendation. Ads in alt-weeklies throughout the state advertise doctors willing to give a consultation to anyone who has one of a seemingly endless list of symptoms and illnesses that might be treatable with medical marijuana. Take the ad for Aldridge Medical Care that runs in the LA Weekly and features a guy wearing a white coat with a stethoscope hanging around his neck. Walk-ins are accepted, the text states, as long as the patient suffers from "pain, migraines, cramps, anxiety, depression, ADHD, nausea, IBS, insomnia, etc."

Once you get the card, it's not much harder to find a shop. On the very same page of the Weekly, the Green Earth Pharmacy offers "Free Samples" to "first time patients with this ad." And for the consumer looking for choices, there's WeedTRACKER.com, which, yes, tracks the varieties of weed available at Harborside and similar centers, allowing patients to rate the quality of each establishment - a Better Business Bureau of sorts. ("[W]e carry over 50 different types of buds, plus all our edibles and concentrates. If we don't have what you are looking for, we probably have something you will like," Harborside promises.) If you're not an official medical-cannabis patient, WeedTRACKER suggests that you "click here"--which sends you directly to Google, a site almost as good at finding pot dispensaries.

We walked through Harborside's metal detector and waited for the two owners, a guy named David Wedding Dress and his partner, Steve DeAngelo. They opened the center in October 2006, on a day that three other clubs in the Bay Area were raided. "We had to decide in that moment whether or not we were really serious about this and whether we were willing to risk arrest for it," said DeAngelo. "And we decided we were gonna open our doors. And we did, and we haven't looked back since. The only way I'll stop doing what I'm doing is if they drag me away in chains. And as soon as they let me out, I'll be back doing it again." After less than a year, the shop was doing $1 million a month in revenue.

In the next room were a half-dozen glassed-over counters where Harborside personnel were describing the various strains of marijuana available to customers. Marijuana's major ingredient, tetrahydrocannabinol, or THC, combines with more than thirty other active agents called cannabinoids. It's not clear how the interaction of THC and cannabinoids affects the user's experience, but THC taken by itself has an effect different from that of marijuana. Different varieties of the plant also have different effects. Cannabis sativa provides a speedy, uplifting high. ("Good for when you want to clean out your garage," said one sales rep.)

Cannabis indica, often recommended for pain relief, knocks you out stone-cold. Most of the pot on sale is a mix of the two, and a young woman behind one counter elaborately explained the benefits of each and whether it had been grown indoors, outdoors, in the shade, or in the open and when in its life cycle it was harvested. "Green Erkle is Purple Erkle picked before it turns purple," she offered. "It's a sativa-indica blend heavier on the sativa, with a nice fruity flavor to it."

For those without a green thumb, the shop offers classes on pot-growing, both indoor and outdoor. Would-be farmers who want a more professional-sounding degree can also enroll at nearby Oaksterdam University.