What must the officer determine at each phase of detection?

At each phase of detection during a DUI investigation, an officer must establish reasonable suspicion. This is crucial because reasonable suspicion is the legal standard that allows an officer to initiate a stop and investigate further.

In the initial observation phase, an officer looks for specific behaviors such as swerving, speeding, or other signs of impaired driving. If these behaviors raise suspicion, the officer can proceed to make contact with the driver. Throughout each subsequent phase, including the interaction and the administration of standardized field sobriety tests, the officer continues to gather evidence that supports or refines that initial reasonable suspicion. Establishing this threshold is essential for ensuring that any evidence gathered thereafter can be used in court.

While other aspects, such as probable cause and documentation, are also important in the broader context of DUI enforcement, the immediate focus during the detection phases is on establishing reasonable suspicion, which justifies the officer's decision to investigate further. Identification of the suspect's history, while relevant in some scenarios, does not directly relate to the immediate requirements of each detection phase.