In North Carolina the alcohol concentration evidence in DWI cases, is only prima  facie evidence that one was impaired while driving.  It does not create a legal presumption that (automatically) requires the fact finder to find guilt (State v. Simmons, 698 S.E.2d 95 (2010) citing State v. Narron, 193 N.C. App. 83, 666 S.E. 2d 865 (2008)).  Every DWI case, must be considered on it’s own individual facts from start to finish.  The Court must consider the totality of the circumstances that encompasses the DWI case, so as to render a fair and impartial ruling.  That is why it is crucial to have an experienced trial attorney help you sort through the facts of your particular case and figure out all triable issues to bring before the Court.