under Michigan law, having a medical marijuana card and having a conceal pistol license at the same time is not illegal and doesn't bar you from possessing any weapons either because under the Michigan medical marijuana act, possessing a card doesn't take away anybodies civil liberties or civil rights.
it is technically illegal under federal law, but the federal govt cannot prosecute anybody who are in medical marijuana states and follow the marijuana law.
theres been many instances where a medical marijuana card holder defended his home and his legal grow operation against intruders with his firearm. the police never took away the home owners firearm are charged him with the crime. but they did arrest and charge the home invaders with a crime.
and also under state law, if you have a medical marijuana card, the state cannot pass that info to any government agency including the federal govt.
so if you have a medical marijuana card and want a cpl , you legally can go ahead and do so.
any questions?