I think I read in this paper that a device has been developed in Edmonton.  It involves taking a swab from the inside of the mouth and testing in a machine that can give immediate results.  This suggests saliva can determine intoxicant levels.  

It is also my understanding that the present laws in effect can temporarily suspend a license and not result in a criminal charge or loss of license.  These laws are about to be altered, remembering that they fall under narcotics control- a federal mandate.