The successful defense of the DUI will most likely hinge on validity of the UA test which would be controlled by the order which authorized the UA test. Sometimes a Court will order UA's based upon "probable cause" of use while others will allow them to be "random" or the discrection of probation. In any event, the "under the influence" part is somewhat of a vague term as there is almost strict liability (i.e. the mere presence of a drug in your system is enough without the need to show that...