Miss this idea after a crash or DUI stop, and a breath test can look more damning than you expect. The absorptive phase is the period after someone drinks alcohol but before the body has fully absorbed it into the bloodstream. During that window, blood alcohol concentration (BAC) is still rising, even if the person has stopped drinking and feels fine to drive.

That matters because test results taken later may show a higher BAC than the person had at the actual time of driving. In a DUI case, the absorptive phase can become part of a defense challenging whether a breath or blood result truly reflects the driver's condition on the road. Lawyers and toxicology experts may look at when the person drank, what they ate, body size, medications, and how much time passed before testing. That analysis is often called retrograde extrapolation.

In Washington, a driver can be charged under RCW 46.61.502 if the BAC is 0.08 or higher within two hours of driving. Because of that two-hour rule, the absorptive phase can be central in a DUI case, especially after a stop in heavy I-5 traffic or a delayed investigation after a winter wreck. It can also affect an injury claim if the other side argues impairment based only on a later test result rather than what was happening at the moment of the collision.