Not the same thing as the official breath machine at the station, and not the final word on whether someone was legally drunk. A preliminary breath test is the handheld roadside breath test an officer may use during a traffic stop to get a quick estimate of alcohol in a driver's system. It helps the officer decide whether there is probable cause for a DUI arrest, but it is usually treated differently from an evidentiary chemical test done later under stricter procedures.

On the ground, that difference matters. A roadside device can shape what happens next - field sobriety tests, arrest, towing, and a later breath test or blood test - but the defense may challenge how the device was used, calibrated, or interpreted. If a crash happened during Alaska's long dark winter commute, when visibility can drop close to zero, a preliminary reading may be only one piece of the story. Weather, driving behavior, witness statements, and road conditions still matter.

For an injury claim, a preliminary breath test can push settlement talks hard in one direction or the other. A positive result may support negligence arguments against the impaired driver. But if the injured person also had alcohol in their system, Alaska's modified comparative fault rule can reduce damages, and under Alaska Stat. § 09.17.060 (2024), recovery is barred if that person is 50% or more at fault.