Maryland  |  DUI Law

I pulled my car off the road because I was not feeling well. The park police found me asleep/in my car which was turned off and pulled off the road. When i woke up they took me to a precinct and drew blood then put me in a jail cell for about twenty mins. Then took me to a subway station (at three in the morning) and then as they are about to leave placed tickets in my hand. I walked home as the subway was not operating that early. When I read the tickets the signature section indicated that I "refused to sign". My question is if i wasn't driving my car and the car was not turned on and they said that they found a small amount of marijuana and/or minor cds in my car do they have a right to even charge me with possession the charge as well as the dui (If i wasn't driving and the car was not on and was pulled over on the road). Also, do they even have the right to search my car if they didnt see me driving and my car?