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Blood Tests

Colorado DUI Blood Tests

Informed Guidance from a Denver DUI Lawyer

Blood alcohol concentration is expressed in terms of the "number of grams of alcohol in every 100 milliliters of blood". When we find that a person has a BAC of 0.08, that means that there is one-eighth (0.08) of a gram of alcohol in any given 100 milliliter sample of blood. One-eighth of a gram is equal to one hundred milligrams (a milligram is one-thousandth of a gram). So, at a BAC of 0.08, the person has 100 milligrams of alcohol in every 100 milliliters of blood, or exactly one milligram per milliliter. If a person has a BAC of 0.08 it means there are 0.08 grams of pure ethanol in every 100 milliliter ("percent") of his/her blood.

Blood Alcohol Content Test Validity

The amount of ethyl alcohol in the blood is of only secondary interest in most DUI cases with a blood test. It is the amount of alcohol actually absorbed into the brain that will affect the individual's ability to perceive, make judgments, coordinate movements, and safely operate a motor vehicle. But in DUI cases there is no practical means of measuring the alcohol absorbed by the body beyond that found in the bloodstream, or, even further removed, in breath.

Since the bones, brain, and fatty tissue contain a much lower percentage of water than does blood—and since the alcohol level in blood is about 17 percent higher than that in the soft tissues—the concentration of alcohol in the entire body, including the brain, is always less than that in the blood.

Breath Tests vs. Blood Tests

In Colorado, you have the choice between a blood test, breath test, or refusal. If you choose a blood test, your blood should be drawn by a certified phlebotomist. A "DUI Blood Kit" should be used to prep your arm and to draw two vials of blood. One vial will be used and tested by the State to determine your blood alcohol content and the other vial is for you to have tested at a certified independent laboratory of your choice.

Blood alcohol tests will be done on "whole blood" rather than "blood serum". Blood serum tests can be 25 percent to 33 percent higher than those of whole blood. For the purpose of a DUI investigation, whole blood should be tested. Oftentimes hospitals will test blood serum for faster results on your BAC. A hospital may also use an alcohol swab to prep your arm before drawing blood which can contaminate the sample.

Many factors can affect how the body processes alcohol and the validity of blood alcohol testing. Blood alcohol tests are more accurate than breath tests; however, a knowledgeable and experienced Denver DUI lawyer will know how to attack a blood test to determine the validity and scientific reliability of the sample.

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