Before an officer can make any kind of traffic stop, including DWI, the officer must have reasonable suspicion to stop the vehicle.  Reasonable suspicion can be a confusing standard, but it is important to understand it in the DWI context.   This is particularly so since a lack of reasonable suspicion may form a basis for a defense to your DWI charges.

As a legal standard, reasonable suspicion is lower than probable cause but higher than just a “hunch.”  To show reasonable suspicion, an officer must show “specific articulable facts” from which he or she drew “rational inferences” that the law was being violated.

Reasonable suspicion is based on the “totality of the circumstances” surrounding the situation.  The time of night, the proximity to a nightclub, a particular road’s frequency of drunk drivers, the driver’s actions behind the wheel, etc. are all relevant circumstances in deciding whether the officer had reasonable suspicion to stop the vehicle.  An officer must be able to explain to a court what he or she saw and why he or she believed that the law was being violated.

A court will consider several circumstances in determining whether there was reasonable suspicion to stop the driver.  These include:

(1) the specific facts that the officer was aware of,

(2) whether the inferences the officer drew from these facts were reasonable, and

(3) whether based on these facts and inferences the officer was reasonable in believing that a law had been violated.

A hunch on the part of the officer is not sufficient for reasonable suspicion.  An officer has to have articulable, concrete facts on which he or she based an inference that the law was being broken.  For example, the court in State v. Lackey found that police did not have reasonable suspicion to stop a car that drove by an accident scene that they were investigating twice.  The court held that there were many reasons why a car would drive by an accident scene more than once on the particular road and that the officers’ hunch that the driver was involved in the accident that they were investigating did not rise to the level of reasonable suspicion.

A driver’s actions prior to a traffic stop may give an officer reasonable suspicion that the person is driving under the influence of drugs or alcohol.  These can include driving at erratic speeds, driving at night with no headlights, and failing to proceed after a light has turned green.  “Failure to maintain lane” is perhaps the most frequently cited grounds for pulling over a driver.  Generally, evidence of actions like these are sufficient to give an officer reasonable suspicion to stop a driver and initiate a DWI investigation.

At other times, officers may stop a driver for other traffic violations without suspecting DWI.  There are several indications that could give an officer reasonable suspicion of DWI once an officer makes contact with the driver.  These include the obvious bloodshot eyes, slurred speech, the smell of alcohol, and open containers.  It might also include difficulty in responding to questions, difficulty finding license and registration, difficulty getting a license out of a wallet or purse and so on.

Sometimes, an officer may be incorrect about what he or she initially believes is reasonable suspicion.  For example, an officer may believe that an oncoming vehicle is failing to keep its lane.  The officer may later discover that the driver was unable to keep his lane due to construction or other impediment on the roadway that was not initially visible from the officer’s viewpoint.  Even when the reasonable suspicion is mistaken, the court may find that a traffic stop was lawful if the officer made a reasonable mistake.  This is turn can lead to a DWI investigation.

However, if the court finds that the officer’s mistake was not reasonable, the prosecution’s case will fail.  A determination of reasonable suspicion will depend on the totality of the circumstances.  These are far too numerous and possibly complex to cover here.  These should be discussed in depth with your criminal defense attorney.