Wow, you just asked a really, really big question. Marijuana is a legal, and illegal substance, depending on who's holding the handcuffs. The U.S. Constitution makes it so that States have the right to decree their own specific laws, as long as they are not against any existing Constitutional law. There is only one law in the Constitution against the consumption of any particular substance, and it was repealed by a later amendment.
However, for, um, various reasons, in 1970, Congress created the Controlled Substance Act, making Marijuana, along with Heroin, Cocaine and Meth Amphetamine, a schedule 1 drug--(A) The drug or other substance has high potential for abuse.(B) The drug or other substance has no currently accepted medical use in treatment in the United States.(C) There is a lack of accepted safety for use of the drug or other substance under medical supervision. This remains the Federal governments firm stance on Marijuana--there was a federal medical marijuana initiative, and there are still, (either 7 or 12, forgive me, I'm high) people who get weed from from Uncle Sam, but that is another story.--
However, the battle is being waged, and California passed both a popular vote(initative 215) and a Senate vote (SB420)to legalize Medical Marijuana here, in our borders. There are really some serious legal battles in our favor against the Department of Health and Human Services, the FDA and State Senates all over the country. It is a difficult battle, but IMHO, the argument against full legalization of Pot have consisted of a "drugs are bad, m'kay" mantra that will eventually be beaten down by proven medical research and sociocultural studies. Weed is good, or at least not as bad as stuff like booze, Compazine, or Prozac.
The History of the banning marijuana in the US is a very interesting story, full of neat conspiracy nut angles, if you wanna lean that way, but a story fascinating enough to rival the Tommy gun days of Prohibition. But I digress.
To answer your question, there are a lot of possible reasons that club in Sacramento got busted, but honestly, been dealing with personal shit these days and haven't been following, so I don't know. Why a lot of club I have read about get busted is that the "Caregiver" status that these cannabis clubs operate under have a great deal of regulations to maintain, one of the biggest is keeping a Non-Profit status. They can't make money, and figuring out how to pay the rent and keeping the bottom line at zero is not something the average pot smoker can master unless they really dot every i and crossed every T. Beside, how they get their pot is about as fair as the competency test Gypsies had to take under Third Reich psychiatrists.
The Feds want this to fail, and many clubs get busted, ironically, on the same day the laws being broken have been written.
As for the reality of your name being in the computer, these are medical records, under State law, and are inadmissible in court. If you are someone who smokes about a few grams a week, privately in your home, what does the DEA want with you? The entire goal of the DEA is to justify their funding by dramatic busts on the news that the current administration can use to show that they are "tough on them thar' drugs."
They've made a few mistakes in the past.
Basically, if you don't feel comfortable being a patient and you can grow your own, go for it and screw the $150 the charge to sign your permission form. I'm just an old guy who has found that pot works for what ails me. I do it under the law because I believe that that law should be there for sick people who need it. I don't begrudge anyone for doing it illegally--I think it is a dumb law. I'm just older and found true love so I don't wanna get busted.
Sorry for the ramble. Believe it or not, I'm incredibly stoned, and a bit verbose at times. Welcome to roll it up. Peace.