Breathalyzer machines are not infallible; they do have problems and they do make errors. The machine needs to be calibrated before it can be completely valid against you, and it needs to be tested.
With this in mind, there are numerous ways a machine can become invalid. There are strict regulations surrounding calibration that the department of forensic science requires before the machine’s result should be counted upon. For this reason, if you have been subject to a breathalyzer test it is almost certainly in your best interest to seek out the counsel of a Fairfax DUI lawyer who will be able to look at the results and see whether any errors or mistakes were made. Call to schedule a free consultation today.
The machine itself must be in a room in the police station in which there’s no ambient alcohol. There can’t be alcohol in the air, or else there is a risk that it could pick up that alcohol. So if the machine was kept in an area in which there were numerous intoxicated people and alcohol may be in the air, that’s another way that a false positive could show up. False positives can also arise from problems with the person who’s blowing into the machine. If the person has mouth alcohol, for example from mouthwash, then that could be a source of an inflated BAC reading.
What the reading is trying to do is determine the amount of alcohol in your blood based upon a sample of your breath. However, if you have a lot of alcohol in your mouth and not in your blood, that shouldn’t be grounds for driving under the influence because the alcohol is not in your blood stream. If you burp, regurgitate or belch before you blow into the machine, that can also be grounds for a false positive or inflated reading because the machine is detecting the alcohol in your mouth and not necessarily the alcohol in your blood stream.
So there are numerous ways to end up with an inflated or a false positive reading on the breathalyzer and there are various defenses that can be set up based upon those errors.
With breathalyzer machines, there’s a requirement for proper calibration in order for a machine to be admissible. There are many ways that censoring can show that the results were inflated or incorrect because a machine had not been calibrated properly. The department of forensic science keeps a log of every time they do any work on the machine, and if there are any problems in those logs or if any problems arise with the machine, a defense attorney should be able to point that out and possibly build a defense around the fact that a BAC reading may be inflated.
Additionally, the machine must run a test in between every single breath sample it takes from a subject. An attorney should be able to obtain the records from the actual breath test that you took on the night in question, look at the calibrations that occurred between each of your breath samples and determine whether there is possibly a problem with the samples based upon the way the machine was working that night.
Breathalyzer machines must be calibrated fairly regularly. There must be no glaring errors in the calibration or maintenance history and the machines must be testing appropriately on the night in question. If there are problems with any of those areas, you might have grounds to challenge the calibration and the accuracy of the results of the breath test.
There is no requirement in the code of Virginia that states that a breathalyzer machine must be calibrated with any specific frequency.
Typically, what you’re looking for is every six months or so, but that is not a requirement to get the results into evidence. However, it can help the court decide whether to trust the results or not. So even though there’s no six-month requirement in the Virginia code, if it’s been three years since the machine was calibrated, the defense attorney probably has a better argument that perhaps the machine was not working right when it took a sample of your breath.
For the most part, these experts know about the issues with breathalyzer technology. Nonetheless, they still use it because it’s the best alternative. There’s nothing better out there that allows for more accurate testing of someone’s blood alcohol content. Additionally, because drunk driving is such a serious offense to the state, the state is willing to risk some errors in machine readings in order to catch drunk drivers and keep them off of the roads.
However, police departments do everything they can to eliminate error, including conducting multiple tests, performing multiple calibrations and providing results of the test to defense counsel. They run various tests themselves for quality assurance so that they are aware of any problems. The upshot is that they put up with the problems because drunk driving is so serious and they need some way to help prove it.
You can absolutely challenge breathalyzer results in court. Your attorney might handle it by trying not to permit the evidence to come in at all because it’s completely unreliable, but that outcome is less likely. More often, the evidence will come in, and your attorney will try to show in court that the results are not reliable.
This has to do with what’s called weight of the evidence: how much weight the judge should give the results. It’s pretty standard that the breathalyzer results will get into evidence, but the way you challenge them is to show that they should be given no weight or very little weight because they are inaccurate due to problems with the calibration or with the machine otherwise.
The results of a breathalyzer in Fairfax are admissible in court and they give a permissive inference that you had a particular BAC at the time you were driving. So if you get arrested in Fairfax at midnight for DUI. Then you blow into the machine at 2:05 a.m. and it gives a reading of 0.09. Most likely, that 0.09 will come into evidence and the court now has a permissive inference that you had a BAC of 0.09 or higher at the time you were driving.
Even though your BAC might have been rising, meaning that it was actually lower than 0.09 at the time you were driving, or even if you might have had a BAC higher than 0.09 and were coming down from that level of intoxication at the time of the reading, the state of Virginia makes the inference that you were at 0.09 at the time of driving if you blow a 0.09 at some point later in the night.
The number that shows up on your certificate is very important because it’s what judges base their rulings on. It’s somewhat hard to rebut, although not impossible.