Massachusetts DWI DUI OUI Field Sobriety Test Police Training Manual

DWI DETECTION PHASE ONE: VEHICLE IN MOTION

Your first task in Phase One: Vehicle in Motion is to observe the vehicle in operation to note any initial cues of a possible DWI violation. At this point you must decide whether there is sufficient cause to stop the vehicle, either to conduct further investigation to determine if the suspect may be impaired, or for another traffic violation. You are not committed to arresting the suspect for DWI based on this initial observation, but rather should concentrate on gathering all relevant evidence that may suggest impairment. Your second task during phase one is to observe the manner in which the suspect responds to your signal to stop, and to note any additional evidence of a DWI violation.

The first task, observing the vehicle in ‘notion, begins when you first notice the vehicle, driver or both. Your attention may he drawn to the vehicle by such things as:

• a moving traffic violation;

• an equipment violation;

• an expired registration or inspection sticker;

• unusual driving actions, such as weaving within a lane or moving at slower than normal speed; or

• “Evidence of drinking” or drugs in vehicle.

If this initial observation discloses vehicle maneuvers or human behaviors that may be associated with impairment, you may develop an initial suspicion of
DWI.

Based upon this initial observation of the vehicle in motion, you must decide whether there is reasonable suspicion to stop the vehicle. At this point you have three choices:

• stop the vehicle;

• continue to observe the vehicle; or

• disregard the vehicle.

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