DUI Blood Test

A DUI blood test is the most reliable and accurate form of DUI chemical testing. If drawn correctly, handled correctly and tested properly, a DUI blood test is the most accurate and reliable direct measure of your blood alcohol level.  The State considers your blood level in its determination of whether or not you are per se driving under the influence (e.g., over the legal alcohol limit), as well as in a “common law” driving while intoxicated case. A DUI breath test is only a “second best” approximation, with numerous factors going into the breathalyzer device’s ability to produce accurate and reliable results.


As opposed to a blood test, which cannot be contaminated by mouth alcohol or a test subject’s “health” issues such as diabetes, all DUI breath tests are subject to “limitations” on their accuracy and reliability.  It is this unavoidable difference that creates numerous challenges to breath testing devices and their accuracy.


Gas Chromatography Mass Spectrophotometry


The most widely-used DUI blood test for alcohol intoxication is “gas chromatography”, which takes a small quantity of your blood (after it is mixed with another chemical in the lab) and (using a small flame) turns this liquid into a vapor. Depending on how quickly this vapor diffuses through a packed column (usually using diatomaceous earth), the machine is able to determine not only the presence or absence of ethyl alcohol in your blood, but the amount as well. A gas chromatograph can also identify other alcohols and similar “chemicals” such as acetone.


The most accepted blood test for drug impairment is “GC-MS” (gas chromatography mass spectrophotometry). GC-MS is the accepted “standard” for precision and accuracy in drug analysis when it is the amount of any drug in your bloodstream that is suspected. This test vaporizes a small quantity of your blood, then analyzes a wide spectrum of possible drugs based on how long the “retention” time is before a substance (drug) is indicated on the spectrum. By determining the pattern of this entire process, comparing it to known standards and retention times kept in the laboratory, the lab technicians and chemists running the test can then determine not only what drugs are in your blood, but how much.


DUI Blood Test Chain of Custody Must Be Followed


For any blood sample that is being used against you in your DUI-DWI case, in order to use any results from these samples against you, the prosecution must prove that your sample was always in possession of someone connected with the State. In other words, the prosecution must be able to demonstrate to the court the various custodians (who had actual physical possession) of this sample from the moment the sample left your body until it was actually analyzed in the appropriate analytical machine. This is what is called the “chain of custody.”


Look for breaks in the chain of custody from blood collection to final analysis.  If there is a break in this chain of custody, an experienced DUI attorney will try to use this in order to get the results of these tests suppressed, so that it cannot be used against you. In some states, the laws are very protective of sloppy and unreliable “chains of custody” by the State, and let a jury or judge consider such evidence for whatever “weight and credibility” it may have.

Search through our online directory of local veteran DUI lawyers and find the one in your area that has successfully represented thousands of DUI clients in complicated druk driving cases. Call us at 844-832-6384 day or night, 365 days a year, including all holidays. An arrest is not a conviction™!