I am going to bash you a bit before I offer any real advice, deal with it. 420n00b may have been a bit harsh, but he's right. A lot of people, myself included, absolutely despise when people come on here and speak in broken English, short hand, text talk, no punctuation, etc. It makes one look unintelligent, and perpetuates stereotypes that stoners are ignorant, lazy, high school drop outs. Now we all know that's not true, so we all need to work towards removing that stereotype and destroying the social stigma attached to smoking. If you're going to be a medical card holder, that makes you an ambassador for the MMJ community, give us a good name. That's why poorly typed out thoughts bother me so much, other people may have other reasons, I don't know.
Now if I were you I would call an attorney. Most people are thinking you really fucked up by telling them you have your card off the bat. Under normal circumstances you would of, but if you're willing to take this to court that could help you. If that is the order of events and they didn't even bother drug testing you, it is blatantly obvious they didn't hire you because of your MMJ card. And doing that would be blatantly illegal.
Sec. 4 (a) of the MICHIGAN MEDICAL MARIHUANA ACT said:
Sec. 4. (a) A qualifying patient who has been issued and possesses a registry identification card shall not be subject to arrest, prosecution, or penalty in any manner, or denied any right or privilege, including but not limited to civil penalty or disciplinary action by a business or occupational or professional licensing board or bureau, for the medical use of marihuana in accordance with this act, provided that the qualifying patient possesses an amount of marihuana that does not exceed 2.5 ounces of usable marihuana, and, if the qualifying patient has not specified that a primary caregiver will be allowed under state law to cultivate marihuana for the qualifying patient, 12 marihuana plants kept in an enclosed, locked facility. Any incidental amount of seeds, stalks, and unusable roots shall also be allowed under state law and shall not be included in this amount.
Refusal of hire sounds like civil penalty to me, which sounds pretty illegal, huh? Not hiring someone because they have a MMJ card is the legal equivalent to not hiring someone because they have a script for vicodin. They can prevent you from using your medication at work, but not at home.
So I'd call around, try and find an attorney who will take this on. Set some legal precedent, son.