North Carolina DWI Chemical Testing

When you are arrested for a drunk driving charge in North Carolina, you will most likely be asked to take a chemical test to establish your level of alcohol or drug impairment. This article is a basic primer on the types of tests used and the procedures followed.

North Carolina DWI Forensic Test Procedures

North Carolina law allows police officers to request that drivers who are charged with "implied consent offenses" undergo a chemical analysis of the alcohol content in their system. Impaired driving of a commercial vehicle and Driving by person less than 21 years old after consuming alcohol or drugs are both implied consent offenses, but Impaired Driving is not.

What kind of test can the officer ask for?

The police officer has the discretion to determine which test the driver will take, but the most common tests are breath tests.

How can the results be used against me?

The results of the test will be admissible in court if the test is given at least twice and the results are within 0.02 of each other.

What if I refuse to take the test?

If the driver refuses to take the test chosen by the officer, the fact that the driver refused is admissible in court and will trigger additional penalties which are explained in the "Suspensions" section.

Can I get my own test if I don't trust the State's result?

The driver has the right to seek an independent test after they are released from police custody.

Can I have an attorney present with me when I'm asked to take the test?

The driver also has the right to request that an attorney or witness be present when they take the test, and may delay taking the test up to 30 minutes to allow such a person to arrive at the scene.

Breath Test Method: North Carolina recently switched over from using the Intoxilyzer 5000 to the Intoxilyzer EC/IR II breath testing device and this is the most common test used for DWI cases. The Intoxilyzer is basically a battery which responds to alcohol with a charge that can be measured to determine the amount of alcohol present.

Blood Sample Analysis: North Carolina also uses the Varian 3800 Gas Chromatograph and the Hewlett-Packard GC/MS (6890/5973) for general blood tests and EMIT and ELISA techniques for drug tests of blood samples.

Gas chromatographs and mass spectrometers use known facts about chemicals (such as molecular weight) to filter and sort all of the components of a sample and measure each separately.

EMIT and ELISA are immunoassay techniques which use antibodies and enzymes to bind to certain compounds (antigens) formed when various drugs are broken down in the body. The test is intended to measure the number of antigens in the sample and to do so, another substance must be added to the mix once the antibodies and enzymes have bonded to the antigens. The extra substances have distinguishing characteristics (such as fluorescing when exposed to light) which can be detected and converted into a reading of the concentration of the drug compounds present in the sample.

Forensic Chemical Analysis in North Carolina DWI Cases is Complex and Prone and to Errors

The information above is just a tongue-tip sample of the complexity of forensic alcohol and drug analysis. The machines and methods used to analyze chemical samples in North Carolina are not foolproof, and a good DWI defense attorney will be able to analyze the data from your test and from the machine's history and maintenance records to determine what errors and issues might exist to help your cause. Make sure that any North Carolina DWI attorney that you hire is an expert in DUI chemical testing science and procedure, and has access to both scientific studies and data, and to expert witnesses to help with the issues specific to your case.