Chemical tests, or a defendant's refusal to submit to these tests, will play a key part in any DUI case. When a driver suspected of DUI gets pulled over, an officer can ask the driver to perform field sobriety tests, and then they might ask a driver to take a chemical test, that is, a blood, breath, or urine test. Now you could usually refuse to perform a field sobriety test, at the expense of raising the officer's suspicion and likely getting arrested. But if you refuse to take a chemical test, then you will be arrested and you will lose your driver's license for up to a year, whether or not you end up getting convicted of your DUI or DWI charge. This is because of implied consent law.

These chemical DUI tests are taken very seriously then, and your entire DUI case could hinge on them. But how accurate are they? It depends on which test is administered. Blood tests are the most reliable, while urine tests are the most inaccurate. But a good DUI lawyer may be able to find a way to defend against any failed chemical test.

The Accuracy of Blood Tests

Short of testing someone's brain cells, this test is the clearest indication of how much alcohol or drugs are in someone's system. That being said, it is possible to argue that the results were too high because the blood sample was not sealed adequately, or that the testing was delayed, causing the sample to thicken or deteriorate. There is even a chance that samples were mislabeled. A skilled attorney could argue any number of things, but the reality is, blood tests are almost always accurate. But even if you fail a blood test, it is possible to find a defense in some other aspect of your case, such as the lawfulness of the arrest.

Breath or "Breathalyzer" Tests

A roadside breath test can provide an officer with an estimate of someone's blood alcohol concentration, since it measures the alcohol on the breath, not in the blood. There is even a greater potential for error in these tests because all it takes is a burp to mess with the test results. An officer is supposed to observe the suspect for a minimum of 20 minutes before the test in order to ensure that they do not burp, vomit, or even spritz their mouth with breath spray, for example, all things that can cause a breathalyzer to read an erroneously high BAC.

There could also be problems with the device itself. In order for a breath test result to be considered reliable, the device must have been recently calibrated and cleaned. You can find out this information in police records. Because there are numerous potential issues with a breath test, a driver could be asked to give two or three breath samples. If you refuse to at any time, you will lose your driver's license.

Urine Tests Are the Least Reliable

And this is why these tests will usually only appear in DUI cases where a blood or breath test could not be taken. This test's inaccuracy can lead to wildly high or wildly low results, however, so the unreliability of this test does not always help out a defendant. Again, because of the mathematical estimates involved with these tests, two samples may be requested of a driver, twenty minutes apart from each other. On top of this, the same errors that are possible in a blood test could appear in a urine test as well, since labs use similar processes to test both types of samples.

Despite the room for error, chemical tests are usually accurate, but there is enough room to throw the results into question when they are close to the legal limit. Consult a DUI attorney on our directory today to learn how you can fight your DUI charge!