DUI Testing

The Tests Used to Determine Whether a Driver is Guilty of DUI

DUI is a specialized type of criminal offense. It involves specific tests that are conducted to determine whether a driver should be charged with and convicted of driving under the influence based upon the laws of the state in which the alleged offense occurred. While every state will have its own set of laws and testing procedures, there are key types of tests and evidence that may be used in an effort to secure a conviction against a driver charged with DUI, OUI or DWI.

An Overview of DUI Tests and Procedures

You can learn more about the key topics associated with DUI testing by reviewing the information we have included below:

Blood Alcohol Concentration (BAC)
A driver's blood alcohol concentration, or BAC, is one of the most important aspects of a DUI case. It is illegal for a driver to operate a vehicle with a BAC of .08% or greater (or lower if an underage or commercial driver), and if a chemical test shows a driver has an unlawful BAC, that driver will likely face criminal charges for DUI. Read more about blood alcohol concentration issues.

Blood Tests
A blood test is generally considered more accurate than a breath test and is administered by taking a sample of a driver's blood to determine its alcohol level. Read more about blood tests.

Breath Tests
Most often, a breath test will be administered to determine a driver's BAC after an arrest for DUI. This is conducted by having the driver blow into a device that measures the concentration of alcohol in his or her breath. Read more about breath tests.

Breath Test Refusals
Refusing a breath or blood test after a DUI arrest is a serious matter. A driver may face license suspension and other penalties for a refusal of this kind, based upon the laws of the state. Read more about refusing a breath test.

Challenging Blood and Breath Tests
The results of a breath test or blood test may be challenged on the basis that the test was conducted improperly, the breath test device malfunctioned, the blood sample was improperly handled or various other scenarios.

Common Faults with Breath Tests
There are specific faults that may be found in breath testing conducted in association with DUI charges. The breath test device, for example, may be improperly calibrated or may malfunction. The test may be administered improperly.

Field Sobriety Tests
Used to determine whether a driver's normal abilities, such as balance and coordination, are impaired as a result of alcohol or drugs, field sobriety tests are an important part of how an officer will establish probable cause to make an arrest for DUI. Read more about field sobriety tests.

Implied Consent
Each state has its own version of Implied Consent laws, which essentially involve a driver's "implied" consent to agree to chemical testing if he or she is lawfully pulled over and arrested for DUI. As such, a driver may face penalties for refusing a breath or blood test after a DUI arrest. Read more about implied consent.

Roadside/Portable Breath Tests
In some cases, an officer may request that a driver submit to a portable breath test at the roadside. Depending on the jurisdiction and whether the driver is under the age of 21, the driver may be able to politely refuse this type of breath test without fear of facing penalties.

Sobriety Checkpoints
A sobriety checkpoint is a type of roadblock set up in order to allow for the random testing of drivers to determine whether they are driving under the influence of alcohol or drugs. There are specific rules and procedures that must be followed at DUI roadblocks to ensure they do not violate drivers' rights.

Find a local DUI attorneywho can help you better understand DUI testing and your legal rights.