Breathalyzer Accuracy
In all drunk driving cases, the prosecution must prove that the defendant's blood alcohol concentration at the time of the offense was at or above a statutory limit. In many states, the limit is .10 percent, but in others such as Texas it is .08, and there is a national movement afoot to make that the limit in all states. In order to prove the requisite level of alcohol in the blood of someone arrested for drunk driving, it is necessary to obtain a suitable sample of the arrestee's blood, urine, or hair at the time of arrest. The use of a breath test is by far the most popular scientific method for establishing that drunk driving has occurred. Some defendants, however, have been able to successfully challenge the results of such tests in court, thereby preventing a conviction.
The State of Texas uses a machine called the Intoxilyzer 5000, which is commonly referred to as a "breathalyzer." Breath testing is predicated on Henry’s law of physics, which states that if temperature, and pressure is held constant the substances in the corresponding gases and liquids will reach equilibrium and will be present in equal proportions. This means that the same concentration of a substance will be present in liquid and gaseous states. The problem is that if someone’s temperature is above 98.6 they will probably have a higher breath test result.
- The Intoxilyzer 5000 is supposed to measure how many grams of alcohol/ethanol per 210 liters of breath is in your breath. The sample chamber of the Intoxilyzer 5000 is 81 cubic centimeters or 81 cubic millimeters. If there is any error in the sample chamber it is magnified 2592 times.
- The sample chamber is never cleaned and is replaced only about once a year. There creates a great possibility of contamination in the chamber. This contamination may affect the testing sample of someone who blows into the machine.
- Researchers have found that substances such as Acetaldehyde, acetone, and Toulene may incorrectly read as ethanol during testing.
- The machine is a self-testing machine. It is supposed to tell operators when there is a malfunction. The problem is that the operators and supervisors of the machine never perform any independent tests to see if the self-checking feature of the machine actually works.
- The manufacturer does not warranty the Intoxilyzer 5000 for accurate and reliable breath testing.
- The Intoxilyzer also assumes that everyone tested will have a blood/breath ration of 2100/1 (i.e. 2100 parts of alcohol in the breath for every 1 part of alcohol in the blood). If a person has a higher blood/breath ratio (i.e. 2400/1) the test will not be adversely affected by this assumption. However a person with a lower blood/breath ratio will be adversely affected because the Intoxilyzer will erroneously read too high, thus a person who should test at .05 or .06 could actually test well above a .08. Additionally, scientists have documented people with blood/breath ratios as low as 1100/1.
- A person with a fever will have a higher breath test reading than an identical person without a fever. Therefore, the temperature of your body can affect what the Intoxilyzer reads, and your body temperature has nothing to do with the amount of alcohol you may have or have not consumed.
- It has an acceptable rate of error of .02. This means that if the machine tested a subject and the test result came back .08 and then on a second test the result was .10 this would be within an acceptable margin of error for the machine. An everyday example is if you are stopped and arrested for DUI and take a breath test, and you blow a 0.080, when your actual alcohol content is something less, you still face the additional charge of driving with a .08 or higher. Very scary.
- Another problem with the results of the Intoxilyzer 5000 is that it measures what your breath alcohol content is at the time of the test and not while you were driving. A person who has been drinking is either in the process of absorption or elimination. During absorption one’s alcohol concentration is generally increasing. During elimination ones alcohol concentration is generally decreasing. Without knowing the time, manner, type and physical characteristics of the subject, there is an equal probability that the alcohol concentration prior to testing is higher, lower or the same as at testing.
- The Intoxilyzer 5000 is based on very old technology. The brains of this outfit, a Z-80 microprocessor, which was introduced almost 30 years ago.
An lawyer experienced in drunk driving defense law is in the best position to advise a client on whether the Breathalyzer test results may be subject to challenge in his or her particular case. David A. Breston generally challenges Intoxilyzer 5000 results based on the following grounds:
- The test operator must have a current certification.
- The machine must have a current certification.
- The machine must be calibrated as often as required.
- The mouthpiece must be changed before the test is given.
- There must be a record of the temperature of the calibrating solutions in the machine.
- A log of the tests run must be kept.
- The number of times the calibration solution has been changed must be counted.
Any of these details may show the inaccuracy of Intoxilyzer 5000 results, and Mr. Breston may be able to suppress this false evidence and get the charges against you dropped.
Contact David A. Breston DWI attorney in Houston or call (713) 224-4040 for a free consultation.
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