Cab I be arrested for medical Marijuana near a school zone?

I've been curious about getting a medical card for marijiana, but I live within a school zone. Very close actually, 2 houses away. I was wondering, if i had a medical card and was driving home after purchasing Marijuana and had it in my car, then pulled over in front of my house, or near any school zone in general, could I be arrested for possession of drugs in a school zone even though I have a medical card?