In almost all Arizona DUI cases a police officer will make an arrest without an arrest warrant. Police are permitted to make such warrantless arrests if they possess probable cause.
Probable Cause in DUI Cases
To make a lawful DUI arrest in Arizona police officers must have “probable cause” to believe the person was driving under the influence of alcohol (DUI). Arizona has codified this probable cause requirement in Arizona Revised Statute §13-3883.
Arizona courts have defined probable cause as “such a state of facts as would lead a reasonable man of ordinary caution or prudence to believe and consciously entertain a strong suspicion of guilty.” State v. Emery, 131 Ariz. 493, 642 P.2d 838 (1982). When the constitutional validity of an arrest is challenged, the court must decide if the facts available to the officer at the moment of arrest “warrant a man of reasonable caution in the belief” that an offense has been committed. Carroll v. United States, 267 U.S. 132, 45 S.Ct. 280, 69 L.Ed. 543 (1925).
In Arizona DUI cases, the determination to arrest is based on the what the officer has observed at the time of arrest. At that time, was it reasonable for him to believe the person was driving under the influence of alcohol?
At the same time, a warrantless search is still presumptively unreasonable under the 4th amendment “subject to only a few specifically established…exceptions.” State v. Fisher, 141 Ariz. 227, 686 P.2d 750 (1980). The also holds true under Article 2 §8 of the Arizona Constitution. State v. DeWitt, 184 Ariz. 464, 910 P.2d 9 (1996).
In order for a police officer to make an arrest for DUI he must have actually observed specific symptoms of impairment. After making these observations, it must be reasonable for the officer, based on his training, to make the arrest. A mere hunch or unsupported suspicion is not enough to make an arrest. The facts surrounding any field tests performed at the scene will be strongly considered in making the determination of probable cause.