| A breathalyzer or breath test result showing a blood | | | | environmental, biological, and physical circumstances. A |
| alcohol concentration (BAC) over the legal limit can be | | | | test administered by an untrained police officer may |
| one of the most damaging pieces of evidence in the | | | | produce inaccurate or unreliable readings. |
| context of a driving while intoxicated (DWI) or driving | | | | Absorption Defense |
| under the influence (DUI) trial. Though damaging, | | | | The absorption of alcohol into the bloodstream takes |
| however, breathalyzer evidence is not ironclad. A | | | | time. By some estimates, it may take up to two hours |
| variety of factors may cause false or inaccurate | | | | for consumed alcohol to reach equilibrium distribution |
| readings, allowing DWI defense lawyers to challenge | | | | throughout the body. Breathalyzer tests administered |
| their reliability in court. | | | | during this period can produce inaccurate results, since |
| Common ways to dispute breathalyzer test results | | | | alcohol content is inconsistent in different areas of the |
| include: | | | | body. Furthermore, if alcohol has not yet been |
| Calibration Error | | | | absorbed into the bloodstream, it does not contribute |
| Like any machine, breathalyzers degrade and become | | | | to a person's level of intoxication. |
| less sensitive over time. Proper calibration is needed to | | | | Biological Variables |
| ensure that results are accurate. Evidence that a | | | | Breath test results are based on a standard |
| machine was not properly adjusted and/or maintained | | | | mathematical formula which relates the amount of |
| may discredit its results. | | | | alcohol on a person's breath with the amount of |
| Operator Qualifications | | | | alcohol present in their bloodstream. This formula, |
| In most states, strict laws are in place to regulate the | | | | however, only applies when all biological variables |
| operation and maintenance of breath test machines. | | | | conform to its standards. The ratio of breath alcohol to |
| Because these devices are very sensitive, operators | | | | blood alcohol varies between individuals and over time; |
| must be properly trained to adapt to different | | | | variations in body temperature can also affect results. |