Breath Tests and Drunk Driving Arrests


In most states, a breath test can be used as presumptive evidence in your trial for DUI. For every crime, the burden of proof is on the state, except when evidence is considered to be presumptive. When evidence is presumptive, the burden of proof shifts to you to disprove the evidence against you. In many DUI cases, a breath test showing a blood alcohol content of 0.08% or greater is presumptive evidence of being under the influence of alcohol.

A breath test measures the concentration of alcohol in your breath to estimate your BAC. With breathalyzers and BAC, the conversion assumes you're an average person. The breath test conversion doesn't take into account whether you're a man or woman, your height and weight, what you've eaten or how quickly your body metabolizes alcohol compared to an average person.

Breath tests may be the most common and powerful form of evidence in a drunk driving case, and breathalyzers are even becoming apparent at high school proms to prevent underage drinking and driving.

Refusing a Breath Test

Refusing a breathalyzer test in most states will mean automatic suspension of a driver's license. In some states, refusing to submit to a breath test can be used as presumptive evidence in a DUI case. Many states like Rhode Island and South Carolina have already made or are trying to make drunk driving penalties for breathalyzer refusals tougher.

In some cases, you can request a blood test in place of a breath test. Some states allow for the forcible drawing of your blood for a BAC test, especially after an accident. There is also a growing trend toward obtaining warrants to draw blood in refusal cases.

Challenging Breath Test Results

A DUI lawyer can attempt to show that the person facing the DUI charge is not the average person and standard formulas for conversion from breath alcohol concentration to BAC do not apply.

Evidence can be introduced that shows the suspect has recently been exposed to chemical compounds containing alcohol that increased breath alcohol concentration without raising blood alcohol content. It's also possible to try to demonstrate that the breath sample was not handled correctly or the breathalyzer was not functioning properly.

In most states, an independent test of a breath sample can be requested. The state would supply a second sample of the suspect's breath to an independent lab of his or her choosing. If the independent lab's test is very different from the original breath test, there may be sufficient evidence to fight the DUI offense.

Learn More about Breath Tests with a DUI Lawyer

If you've been charged with DUI offense and you submitted to a breath test, you may still be able to challenge the results of the test. You should understand how a breath test can be used as evidence for a DUI conviction. Speak to a DUI lawyer about your charges by filling out the above form or calling 877-349-1311. Get started fighting your DUI charge.


