In Colorado, the “rising blood alcohol” defense is often used to fight DUI charges. You argue that your BAC was below the limit while driving, but rose to be above the limit by the time the blood or breath test was taken since the alcohol was still being absorbed into your body.

This scenario assumes that you consumed most of the alcohol shortly before getting pulled over.

DUI blood testing

One of the ways in which Colorado prosecutors prove drunk driving is through a DUI blood test or DUI breath test. DUI chemical tests measure the amount of alcohol present in your blood. This is known as your “BAC” – your blood alcohol concentration or blood alcohol content.

There is a delay between when you drink and when the alcohol becomes detectable in your blood. As a result, you might not be legally intoxicated when you are pulled over.

Yet, when you take a chemical test, you might be over Colorado’s absolute BAC limit of .08% for a Colorado DUI “per se”.

Rising blood alcohol as a defense

Like all the best Colorado DUI defense lawyers, we understand the science behind rising blood alcohol levels. We invite you to contact our caring DUI attorneys for a consultation to find out if your blood level was on the rise when you were arrested for:

• Colorado DUI,
• Colorado DUI “per se”,
• Colorado DWAI,
• Colorado UDD, or another
• Colorado drunk driving offense.

 

In this article, our top Denver DUI attorneys explain:

• 1. How your system absorbs alcohol
• 2. Rising blood alcohol and DUI chemical tests
• 3. Proving rising blood alcohol

1. How your system absorbs alcohol

When you drink, most of the alcohol is absorbed in your digestive tract. From there, it passes into your blood.

Some of the alcohol is excreted in your breath and urine. The rest is carried to your organs, including your brain and liver.¹

The liver metabolizes alcohol so that your system can eliminate it, but it can only detoxify a certain amount of alcohol at a time. Until it can complete the process, some of the alcohol remains in your blood.² This is known as your

• blood alcohol concentration or
• blood alcohol content (“BAC”).

1.1. How BAC rises

When you consume alcohol, your BAC rises rapidly and steadily until it reaches its maximum level or “peak.” This is where the term “rising blood alcohol” comes from.

BAC peaks on average between 30 minutes and an hour after you stop drinking. Though it can take longer — up to two hours. The precise time varies from person to person and even within the same person, depending on the given day and circumstances.³

1.2. Factors affecting rising BAC

Factors that affect the rate of alcohol absorption include:

• Your physical state,
• Your weight,
• Your gender,
• Whether (and how much) you have eaten, and
• The presence of other substances in your system.

After you stop drinking, your liver eventually catches up. More alcohol is eliminated and less is absorbed, and your BAC then starts to fall at a more gradual rate.

2. Rising blood alcohol and DUI chemical tests

Colorado DUI blood tests are not given right when you are pulled over. Usually, the officer will question you first.

You may be asked to take a preliminary breath test or other roadside sobriety tests before you are arrested. Only then are you taken to a police station or other facility to have a post-arrest DUI chemical test.

2.1. Two hour rule

In Colorado DUI chemical tests must be given within two hours of driving.⁴ For some people, however, their BAC may still be “on the rise.” As a result, you can be legally capable of driving at the time you are pulled over, but over the limit by the time your blood is drawn.

Example: You quickly down a drink and start driving. The alcohol has not yet fully entered your bloodstream, and your BAC could be well below .08% if the police pull you over for a minor traffic violation.

Though if the officer smells alcohol on your breath and arrests you, your BAC could rise to .08% or higher within the two hour window to test your blood—even though you were not drunk at the time you drove.

3. Proving rising blood alcohol

A forensic toxicologist or other expert witnesses can examine your Colorado DUI chemical tests and other evidence. They will use this evidence to establish your personal BAC timeline.

If the DUI defense expert determines that your BAC was on the rise at the time of your arrest, your experienced Colorado DUI lawyer may be able to get the charges against you dropped. Or we can use it to negotiate a plea bargain for a reduced charge that will let you keep your Colorado driver’s license.

If your case goes to trial, your DUI criminal defense attorney can use the evidence to counter the prosecution’s expert witness. At the very least, we may be able to create reasonable doubt for the jury that you were over the legal limit at the time you drove.

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