As in any criminal prosecution, Probable Cause for DUI Arrest to stop the driver of a motor vehicle may be an issue in a drunk driving case. Lacking sufficient cause, any evidence obtained as a result of the stop - which should include all evidence except observations of driving, must be suppressed. Assuming the existence of grounds for the stop, the prosecution must then justify the investigatory detention. Again, if there are insufficient objective and articulable facts upon which to warrant detaining the driver beyond a temporary stop, then a motion to suppress all subsequently-obtained evidence should be made. If successful, this will suppress all evidence but observations and statements made during the brief stop. Finally, if there existed probable cause to detain the individual for a field investigation (field sobriety tests and brief questioning) there must still exist a considerably greater amount of evidence of intoxication to warrant an arrest. (There must also exist the authority to arrest, involving the question of whether the offense was committed in the officer's presence.) Without such cause, evidence obtained after the arrest, consisting in most cases primarily of the blood-alcohol test or refusal, is subject to suppression.
In essence, this usually means in a DUI case that the prosecution must establish a considerably escalating amount of evidence at each of the three stages-stop, detention, and arrest. Lacking the sufficient quantum of evidence at any stage results in suppression of all evidence obtained thereafter.
There are, of course, thousands of federal and California cases interpreting in general terms what constitutes sufficient probable cause to justify stopping, detaining, and arresting a citizen. Certainly such authority should be used in a DUT motion to suppress. It should be clearly understood by defense counsel, however, that a "double standard" appears to exist when it comes to drunk driving situations. Put another way, both the trial and appellate courts often prove more willing to find probable cause in DUI cases than in other types of offenses.