Types of Chemical Tests for DUI

Under Virginia law, chemical tests are to be used at the time of a DUI arrest to confirm the amount of alcohol in a person’s system. This test takes place after the arrest, and the results can be used as evidence to prove that you were driving under the influence.

In most cases for drunk driving, a chemical test is used to measure blood alcohol concentration (BAC). Virginia’s legal limit for adult drivers is 0.08%. For commercial drivers, that limit is lowered to 0.04%, and it is just 0.02% for drivers under the age of 21.

There are several different types of chemical tests for DUI, but these should not be confused with a preliminary breath test (PBT). One is required by law if there is a DUI arrest and the other is optional.

Preliminary Breath Testing in Virginia

If you are pulled over for suspicion of DUI, the police officer may want you to take a field sobriety test. It may seem like a demand at the time, but this is not a mandatory test. You don’t have to participate in any roadside tests that could incriminate you, and this includes taking a preliminary breath test.

A PBT is a handheld breathalyzer test that an officer will use to gauge your BAC. These tests are inaccurate and not required by law. The results can also not be used as evidence against you in a DUI case. Whether you refuse to take this test or not, you may still be arrest for DUI. At this point, the rules change.

Types of Chemical Tests for DUI

Virginia is an implied consent state, meaning drivers are compelled to take a chemical test to measure their BAC after a DUI arrest. Refusing this test will result in additional penalties. If you are charged with DUI, you will be transported to the police station and given a chemical test. There are two types of chemical tests given in Virginia for DUI – breath and blood.

• Breath Analysis. A breathalyzer test is the most common way to measure BAC after a DUI arrest. Sophisticated breath test machines are located in police stations that actively measure BAC using either fuel cell or infrared technology. These tests must meet specific criteria to ensure reliability and accuracy. Even so, they are fallible, and their results can be challenged.
• Blood Analysis. A blood test is another way to measure BAC in the body. A blood sample is drawn, which is supposed to show the most accurate results for BAC. Unfortunately, these results can also vary depending on a variety of factors.

Some states also test urine, but this is an inaccurate and indirect way to measure BAC. It can take alcohol as long as two hours to appear in urine. There are similar errors when testing urine for drugs.

Potential Defenses for DUI Chemical Tests

Just because your chemical test reveals a result above the legal limit, that does not automatically mean that you will be convicted of DUI. You will have a tougher case, but the state must still prove beyond a reasonable doubt that you broke the law.

Not all chemical tests are completely accurate, and this is particularly the case with breath tests. These machines require operator expertise and must be regularly maintained and calibrated to ensure accurate results.

There are both human and machine error defenses against chemical test results. If a test was mis-administered or improperly read, the results should be thrown out. Likewise, the machine could have malfunctioned and delivered an erroneous result.

Biological factors can also affect both breath and blood analysis results. For example, a person taking cough syrup that contains alcohol or ginseng could already have an elevated level of alcohol in their blood. A breath test could even be affected by certain irregular breathing patterns.

Get Experienced DUI Representation

If you have been arrested for DUI in Virginia, you still have legal options. Even if a chemical test revealed that your BAC was above the legal limit, there are certain defenses that might help your case. At Pack Law Group, our skilled and aggressive DUI attorneys will protect your legal rights and do everything possible to shield you from the harsh penalties that can follow a DUI conviction.

We have helped people who have been accused of DUI throughout Virginia’s Roanoke, Bedford, and Lynchburg counties achieve a favorable outcome. Contact us now at 540-586-7225 or reach us online to schedule a free consultation.