Driver stopped by police on highway for driving well below the posted speed limit. Driver exhibits signs of marijuana impairment to include sluggish behavior, green tongue, dilated pupils and confusion. Driver participates in standard field sobriety tests, and a post arrest Drug Recognition Evaluation. Blood test is completed and disclosed presence of active Marijuana metabolite in blood in excess of 5 ng/dl. Defense prepared to challenge DRE protocol. DWI charge dismissed prior to trial.