The case involving Pennsylvania's DUI breath testing was heard in Superior Court late Tuesday morning.
The issue is the accuracy of the system that a Dauphin County judge called flawed. The Commonwealth appealed the judge's decision that prohibited them from entering evidence of blood alcohol content above .16.
They argued the judge was in error because the current breath testing procedure meets state guidelines.
Defense attorney Justin McShane said that breathalyzers are not calibrated beyond .15, and any reading above that would not be accurate and could wrongfully convict innocent people.
McShane says the Superior Court ruling will have an impact on thousands of cases in the Commonwealth.
The State Superior Court could take up to 90 days before announcing its ruling.