If you or someone you know has been charged with driving under the influence (DUI) in Virginia, you may want to learn more about blood alcohol tests. Police officers may use a breath-based test, such as a breathalyzer, at a routine traffic stop. Do you have the right to refuse this test? What’s the difference between breath and blood tests for alcohol content? Know your rights and learn how a high result on a blood alcohol test isn’t always an open-and-shut case.
What Do Blood Alcohol Tests Measure?
Blood alcohol tests, as their name indicates, measure the amount of alcohol in a person’s bloodstream. The result is a number called blood alcohol concentration (BAC). This number is usually expressed as a percentage, but the same number without the percent sign means the same thing.
In the state of Virginia, the legal BAC limit for driving is 0.08%. You might also see this as a BAC of 0.08. This means that for every 10,000 parts of blood, there are 8 parts of alcohol. The alcohol detected by tests are both ethyl alcohol and ethanol. These are the common components of alcoholic drinks, like beer, wine, and spirits.
A person’s BAC can vary based on many factors:
- Number of standard drinks
- Time since the drinks were consumed
- Sex assigned at birth
- Race and ethnicity
- Body weight and composition
- Hormone levels
- Enzyme production and levels
- Medications and food
In this context, a standard drink might be 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of hard liquor. If you order a pint of regular beer at the bar, that’s 16 ounces. This is 33.3% more than a standard drink. Wine and hard liquor with different levels of alcohol content may also be more or less than a standard drink.
Individuals whose BAC tends to increase faster include women, older people, and people who weigh less. If you eat food before and while drinking, this can slow the increase in BAC too. Genetics can affect liver function, which in turn affects how your body metabolizes alcohol.
Potential Problems With BAC Test Results
A blood test is generally the most accurate alcohol test available. This requires drawing blood using a needle. Other tests may use breath or urine samples. All of these tests aim to measure how much alcohol is in your body. And they each have their unique problems and challenges.
A breath test is most often taken at police headquarters. They may also conduct field sobriety tests. The officer may be trained to use a breathalyzer, but they are not a medical professional. Your lawyer may be able to introduce doubt based on how the test was given or how the testing equipment was maintained.
A blood test is usually taken at a hospital, potentially hours after the initial incident. Timing becomes an issue. The amount of alcohol in your bloodstream hours later is likely different from when you were driving. This can introduce a “rising blood alcohol” defense. Interactions with other substances, like marijuana, can impact results.
Testing equipment is subject to human error, too. Samples can get contaminated or be poorly handled. What’s more, lab results can sometimes take several weeks or more.
Alcohol Tolerance and DUI Charges
Building up your tolerance to alcohol does not affect your BAC. Rather, it simply changes how you feel after a certain amount of alcohol. People with higher tolerance may feel less affected by alcohol. In this way, even if someone’s BAC is above the legal limit, they may not feel intoxicated.
To be charged with drinking while intoxicated (DWI) in Virginia, a person must be both intoxicated and have a BAC exceeding the legal limit. Prosecutors must also prove that the person exhibited impairment while driving. This is one of the problems with BAC testing, as it only presents one part of the picture. A skilled Virginia lawyer can present this argument as part of a DUI defense strategy.
Can I Refuse to Take a Blood Alcohol Test?
Virginia has an implied consent law. By using the privilege to drive a car, you consent to being tested for your blood alcohol level. No, you cannot refuse to take a blood alcohol test. This results in a separate offense.
At first refusal, you may lose your driver’s license for 12 months. At the second refusal, within 10 years of the first refusal, the state may suspend your license for three years, issue a $1,000 fine, and put you in jail for six months. A third refusal can result in three years’ suspension, a $2,500 fine, and up to one year in jail.
How a Defense Lawyer Can Help
An experienced DUI lawyer can put together a strong defense and introduce doubt into the prosecution's case. One big example is challenging the results of the blood alcohol test. Are the test results valid? Was the equipment properly maintained? Was the test conducted correctly? The burden of proof falls on the state.
As discussed above, your Virginia defense lawyer can also argue that your BAC was below the legal limit while driving. It was only above the legal limit when the blood test was done hours later. Your lawyer may call in a toxicology expert to your defense. This may be enough to have the DUI charges dropped or dismissed. Even when the charges aren’t dismissed, the right attorney can argue to reduce the punishment.