Rising Blood Alcohol Defense

When the results of a chemical test taken incident to an arrest for DUI reveal a BAC of higher than 0.08, it may at first seem futile to contest the charges. However, based on the facts of the case, a rising blood alcohol defense may be employed in an effort to achieve a positive result in the case.

Driving, the Chemical Test and a Rebuttable Presumption

It may seem obvious, but it is important to remember that the laws that prohibit being under the influence of alcohol or having greater than a 0.08 BAC apply when driving. The typical scenario of a DUI stop, investigation subsequent arrest and transfer back to the police station place the timing of the chemical test a significant period after the suspect was actually driving. Although under California law there is a rebuttable presumption that a chemical test that registers greater than 0.08 and was administered within three hours of the arrest indicates the suspect was driving over the legal limit, that presumption can be overcome with evidence that the BAC at the time of driving was in fact less.

Alcohol Absorption and Elimination

When alcohol is consumed, some of it is immediately metabolized and eliminated through the liver. Based on the amount consumed, some remains in the blood system as indicated by the BAC. Complete elimination will occur at some point after the cessation of drinking, but the typical pattern shows a rapidly and steadily rising BAC until a maximum limit is reached. Most often, this peak limit is reached within 30 minutes to an hour, but it may take as long as two hours based on a number of individual factors, such as the ingestion of food.

Establishing a Rising Blood Alcohol Defense

It is necessary to retain an expert witness who can both explain the general science involved as well as establish the personal BAC of the suspect at the time of driving in contrast to the BAC established by law enforcement from the chemical test after arrest. If for example, the chemical test indicated a BAC of 0.10, it may be successfully argued that the alcohol in the suspect’s system was not fully absorbed while driving. A rising blood alcohol defense can benefit from the establishment of other facts as well. It can be helpful as additional facts if the driver had consumed alcohol shortly before driving and performed relatively well on any field sobriety tests that were administered.