. >> reporter: the driver whoit blake had thc in his bloodstream. he served three years in prison. >> in my view there's a perception that marijuana does not ouimpairike alcohol does. that's not you are impaired. >> repter: currently there's no roadsidee test l a breathalyzer to test for thc, the ingredient that get you high. back on maryland's highways, troopers have been trained to detect marijuana sblns. >> glossdshot eyes, drooping of the weyelids, s exaggerated vements. >> reporter: unlike alcohol, there's no legally impaired limit. troopers say they see people behindhe wheel at night and in the morning too. keeping them busy4 hours a day looking for drivers operating a high speed. >> there's also aowrg debate over the healing power of pot. marijuana is legal in 30 states but there's no proof it works for a variety of symptoms and don't tell that to the people who rely on the drug, including a former miss maryland world winner. >> it really is the miracug >> reporter: this local beauty queen is turning her pain into a platform to promote medica