The court rules last week in the case of Geirrod Stark, who was found guilty in 2010 of driving while impaired.
In its ruling, Judge Pro Tem Jesse Walters overturned the conviction, arguing Stark's blood test results only prove he'd used marijuana recently not the day he was stopped.
There's no question Stark was impaired that day Walters said, but there's no proof that drugs and not some other condition caused his erratic driving.
During his original trial, Stark said he was disoriented because he was dehydrated and hungry.
He said he also suffers from paranoid schizophrenia and bipolar disorder.