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Does A Denver Criminal Defense Attorney Recommend A Breath or Blood Test?

November 15, 2017

Expressed consent laws in Colorado require every driver to consent to either a breath or blood test after being arrested for driving under the influence (DUI). The law also states that the driver can choose whether he wants to take a blood or breath test. Which test does a Denver criminal defense attorney recommend? Here’s what you need to know:

Timing of the Tests

Both breath and blood tests are designed to read your blood alcohol content (BAC). A person’s BAC will rise when the person is drinking alcohol and then continue to elevate for a short time afterwards. Your BAC will be at its highest point anywhere from 15 minutes to one hour after you have stopped drinking. Then, it will slowly start to fall back down as alcohol is processed and removed from your system.

A breath test is typically performed within 20 minutes after the arrest using a handheld breathalyzer device. However, police officers cannot perform a blood test on the side of the road because they are not trained to do so. For this reason, the blood test is typically not performed for about an hour after you are arrested.

Before you decide which test to take, think about the last time you consumed alcohol. If it was right before you got into the car, the breath test may be a better choice because your BAC probably has not peaked yet. See DUI: breath test or blood test.

Inaccurate Readings

A police officer could make a mistake when performing a breath test that leads to an inaccurate result. For example, the breathalyzer must be calibrated on a regular basis. If it’s not, the results could be inaccurate.

Certain medications and over-the-counter products could also affect the results of a breathalyzer test. Taking a swig of mouthwash, which contains alcohol, prior to taking the test could make it appear as if you are intoxicated even if you’re not.


If you choose a blood test, law enforcement officers will request that two vials of blood be taken from your arm. Even though two vials of blood are taken, only the first vial is tested by law enforcement. The second vial of blood will remain in storage so it can be retested if necessary. If you know that you are not drunk, having the opportunity to retest a sample could work out in your favor. The results of the second vial should prove your innocence by showing that there was a mistake made on the first test.

However, if you are under the influence, having a second vial to retest could hurt your case. It will be difficult to prove that the test results were inaccurate if two separate vials both showed that you were under the influence of alcohol. In this case, the retest could actually strengthen the state’s case against you.

Keep this information in mind if you are ever arrested for DUI. If you are charged with DUI, get in touch with the Law Office of John Buckley as soon as possible. John L. Buckley will work tirelessly to fight the charges that have been filed against you. Contact John L. Buckley as soon as possible to schedule a legal consultation regarding your DUI case.