DUI Lawyer Advice: Breathalyzer Vs Blood Test

Criminal Law

If an individual is pulled over by law enforcement for drinking and driving, a breathalyzer or blood test could play a vital role in determining future convictions. Driving under the influence (DUI) is a criminal offense, and DUI lawyers are regularly asked which method best calculates BAC levels. In many states, a blood analysis is mandatory. Many people still want to know, however, which assessment is best immediately after a driver has been taken into custody.

What Is Required By Law?

DUI laws vary from state to state. Typically an officer will ask a suspect to take a field sobriety test or to submit to a breathalyzer examination. The first option consists of three elements: the horizontal gaze nystagmus (HGN), the walk-and-turn, and the one-leg test. It is important to remember that before the arrest is made, both assessments are completely optional. Attorneys usually advise clients not to submit to either, as it can provide undisputable evidence.

If the officer suspects an individual is breaking the law or if a person fails one of the previously mentioned examinations, they are taken into custody. While in detention, many states require a blood or breathalyzer test. In theses instances, many clients want to know which is more likely to produce advantageous results for them. There is no one-size-fits-all solution, and people will have to decide which method is best based on their circumstances.

Blood Analysis

A blood test is considered much more accurate. After a technician takes a specimen, some of that sample will remain securely stored for use in the case. This means that a defense attorney could request an examination by a different laboratory, ensuring a strong defense. Those who believe they are indeed over the limit should not agree to this option.


A breathalyzer is considered a less reliable method to measure BAC. Some independent studies have found that these results could vary by as much as 15 percent from true levels. Factors that could contribute to inaccurate readings include body temperature, machine temperature, the amount of hematocrit in the blood, or improper calibration. There are also several common myths involving ways to cheat these tests. Using mouthwash, chewing gum, having a penny under the tongue, as well as many other techniques for cheating the system do not work. In fact, mouthwash can even negatively impact results. Depending on the judge and local court history, these results could be considered acceptable or inaccurate as evidence. In some cases, breathalyzer results can be contested by a DUI lawyer.

Which Method Should One Choose?

Breathalyzer results allow attorneys more leverage, possibly leading to a better outcome. The choice between the two methods is dependent on the person. A DUI lawyer should be called immediately after a driver is taken into custody. They can provide individualized advice on which analysis would be better in a specific situation. If the results are not favorable, the attorney can start building a defense strategy.