How accurate is a DUI breath test? 66 Answers as of August 04, 2011

The machines in use now are very accurate as long as all the procedures and protocols have been followed.

There are two breath tests. One is a PBT which is a hand held device officers use on the scene. It is an approximation used for a determination of probable cause. The certified breath test is administered at the jail, police station, hospital or some other facility where a certified breathalyzer is maintained. This is the test required by the Implied Consent law. Refusal to take this test will, with only a few exceptions, result in your license being suspended. These machines are calibrated periodically and the test operators are re certified periodically. These tests are considered to be reliable and admissible as evidence. A lawyer knows how to investigate as to whether or not there is a question as to the certification of the machine and operator.

If you blew a .08% you should be able to fight your charges. I do not know the rest of your facts so I can't tell you too much, but it certainly sounds like a very treatable case. I handle a lot of DUI/OUI/DWI cases and I have taken almost all .08% BTs to trial. In fact, I don't think I have ever lost an OUI/DUI/DWI with a .08% BT. This is no guarantee of your result, but generally, it sounds like a good case to take to trial (the only other option would be to tender a plea agreement since no DA will dismiss an OUI charge with a .08 BT).

An expert witness for hte defense will testify that the test has a margin of error of 10%. This would put you under the legal limit for DUI. You should be able to get the charge reduced to negligent driving in the first degree.

How accurate is a DUI breath test? Very inaccurate. DWI defense is a main practice area of our firm. You should consider retaining our office.

The breath testing machine has to meet certain criteria and be certified on a regular basis. While in most instances this is done, checking the certification records might lead to a defense.

Yes. The margin of error is + or - 0.01. If you blew 0.083, then the actual result is between 0.073 and 0.093.

The machine does have a margin of error. Any result close to .08 is a winnable case. You will probably need an expert witness, however.

A breath test is an approximation. No one can tell you how accurate it is.

You can fight it, however, it can be expensive. Your attorney will have to conduct a lot of discovery regarding the machine and the police procedures of the particular police department that administered it, as well as, possibly hiring an expert. Contact an attorney.

Like any piece of machinery, that are not infallible and often make errors. A lot can go into making a breathalyzer inaccurate. Retain an experienced DUI attorney who can review the police report and lab results for any errors that could get the charges reduced or dismissed. A good attorney through discovery and knowledge of the science will be able to say if your results were inaccurate. They also have to be properly serviced, maintained, and calibrated.

DUI breath tests can have many issues. They may not be calibrated or maintained properly. There are outside factors that can affect their accuracy including breath temperature, mouth alcohol, GERD (ie. acid reflux), etc. This sounds like a good case to fight. I have gotten DUI charges dismissed and reduced to non alcohol related charges in cases that sound similar to what you are describing.

There is a great chance you can beat that, especially if you did not blab to the cops how much you had to drink and when. There is much to attack in breath testing, and in DUIs in general.

Your question is a good one, however, there are volumes written on the subject. If you fight a case based on the test, be ready to pay for it. The cost of an expert will be in the $1,000's, and the attorney fees will be on top of that. Unfortunately, unless you are facing prison time, (in which case you may want to spend all that you can afford to avoid it), or you have available funds, or you have a patently clear error with the test, the cost can be unrealistically prohibitive. You should consider hiring an attorney to have your case reviewed so that you can make appropriate decisions.

Yes, you can certainly try to defend the charge of DUI. In some cases we can raise enough "reasonable doubt" to get a defense verdict. In some cases the cops do not do everything right and provide us with a defense. In other cases, a toxicologist might be used as an expert witness. Fighting one of these case can be very expensive and very risky. In most cases the defendant (you) will be able to negotiate a plea bargain that will avoid a conviction and also allow you to get your full driving privileges back as soon as possible.

Do you mean it was .08 in the field or at the station? The handheld breathalyzer in the field is not very reliable and is not allowed as evidence. The breathalyzer at the station is much more reliable but may be challenged in a number of ways. Also, are you sure the case has been issued? Just because you are arrested doesn't necessarily mean you will be charged. The DA has until the first court date to decide whether to issue the case. Often, if the result is borderline or questionable, the case will not be issued. Assuming it is, a BA level that low will most likely get you an offer of a wet reckless. You may be able to do better depending on the other facts of the case. If you don't want to take any of the offers, a borderline case obviously has the best chances of a victory.

They are generally accurate, but can be challenged, especially in a matter as close as the reading in this case. Since you were just over the limit, your lawyer should be able to negotiate a plea to a dui (driving while impaired), which is a non-criminal violation.

The breathalyzer machine is very accurate but can be effected by burping, acid reflux, alcohol coming up from your stomach into your mouth, and other things. You can get an Impaired violation with a low score of .08.

In Washington the courts have recently addressed this question. As with most measurements the BAC as measured by breath test doesn't actually tell you what your BAC is, rather, it is one measurement that represents an approximation of what your BAC is. Courts here are trying to account for that inaccuracy by applying a "confidence interval" meaning, a spread of numbers that should include your actual BAC based on that particular machine's history. So, for example, let's suppose a suspect blows .08. After applying the confidence interval for the particular machine the suspect's BAC could be anywhere between .075 and .085 (the confidence interval is different for every machine, this is not necessarily indicative of your personal situation). That being said you should be aware that you can be convicted of DUI even if you blow under the limit if your driving was "effected to any appreciable degree" by alcohol or drugs. You should contact an experienced DUI attorney to discuss the particulars of your case. Thank you,

Breath testing equipment is generally accurate. The most fertile area of attack generally is whether the arresting and testing officers followed the require procedure and the assistance of an attorney would be very helpful.

There are a lot of factors to review to determine whether the breath test was proper. You should hire a lawyer to look at all the evidence and try to avoid a DUI conviction.

There is a built in tolerance in the results of approximately 0.01 +or-. Many other factors can affect the result, and make them unreliable. I would need more information to answer your question. Please call my office during business hours. Thanks for the inquiry.

Not very accurate at all. The margin of error is at least a 0.02, and someone who has had nothing to drink could still be over the limit. For example, if you just ate and have soy sauce in your mouth, you'll probably blow a 0.02 on that alone. Consider hiring a DUI specialist. That is your best chance of getting the DUI reduced or dismissed.

There are a lot of factors that go into fighting the accuracy of the breath test. I estimate that you can knock 30% off the BAC, with the proper expert testimony about the problems with the tests. Even the manufacturers and police technicians who testify will admit that the machines have a range of .01%. So your BAC could have been from .07 .09 if it read .08. You are just as likely to be below the limit as above it, which is not good enough for reasonable doubt. There is also a recently decided case: People v. Vangelder, that expands the defense's right to proffer evidence of the inherent problems with the machines. In Vangelder, the expert testified that when the police ask the subject to blow the air he expands has alcohol from alveolar region of the lungs as well as alcohol that was collected in the sample on the way down the throat and back up the throat. So the sample doesn't read what it purports to read, alveolar air. Thus the readings of the machine are inflated. You should definitely fight the results. Call me, this is something I can help you with.

You can always fight a breath test. There are a lot of things that have to be considered to determine whether a BAC result is valid and whether a jury would even hear of the BAC re sult if this went to trial The closer the BAC result is to .08, the easier it is to fight the case in court and to negotiate a favorable resolution. A good defense attorney with DUI experience is needed to effectively handle these issues.

there are lots of ways to fight breath tests - every day we seem to find new ways that they are inaccurate - but, being under .08 just means that you were DWAI (.05-.08). That has many of the consequences as DUI. The only way to truly fight one of these is to get a real DUI attorney.

Fight it. Fight it. Fight it. The test are great tools but they are not conclusive. There are a number of things that can cause them to register high. Call a qualified dwi attorney. Ask the attorney if they can explain exactly how the breath machine works and what problems can cause an artificially high result. There are a number of problems and cause for concern.

7-28-11 Most criminal defense attorneys do not believe that the breath test is all that reliable. However, the courts and the Alabama Department of Public Safety place high value in the results. The reliability can be questioned at the trial. It has been my experience in trial that a jury does not always strictly follow the results of the breath test in considering whether to acquit or convict.

The accuracy of breath tests is under near constant attack by DUI attorneys, particularly here in the State of Washington. Over the past several years hundreds of cases have been dismissed or downgraded based on numerous problems with the breath test machines, the State Patrol Lab and other issues. Tests that are right on or near the .08 line are particularly worth challenging as a basis for a reduction, dismissal or victory at trial. But you need a good attorney experienced in DUI defense in order to make your case that the test was flawed or the machine was inaccurate.

There are many factors in determining the accuracy of a breath test. It is my opinion that the portable breath testing devise is great at detecting alcohol but lacks precision as to the amount. There are lots of variables involved which a DWI lawyer will be able to explain starting with physiological, medical, absorption and elimination plus application of good protocols in administering the breath test. It is my opinion that if you provided a breath sample of .08 that you very likely have a good case and a good DWI lawyer should prevail depending on the court and other facts.

There is not a simple answer to this question I suggest you schedule a free initial consultation with a lawyer.

Breath is much less accurate than blood, and a .08 on a breath test will usually get you an offer of wet reckless. The police do not save the breath ampoule so there is no re-testing on a breath sample. the issue would be raised in trial in either the questioning of the prosecution expert or in bringing in a defense expert.

Entirely accurate until proven otherwise in independent testing by your retained Expert who would have to so testify at trial. The procedure for use does two accuracy tests automatically as part of the process. Of course you can fight the charges. When arrested or charged with any crime, the proper questions are, can any evidence obtained in a test, search or confession be used against you, and can you be convicted, and what can you do? Raise all possible defenses with whatever admissible and credible witnesses, evidence, facts and sympathies are available for legal arguments, for evidence suppression or other motions, or at trial. Not exactly a do it yourself project in court for someone who does not know how to effectively represent himself against a professional prosecutor intending to convict and jail you. If you don't know how to do these things effectively, then hire an attorney that does, who will try to get a dismissal, diversion, reduction or other decent outcome through plea bargain, or take it to trial if appropriate. If serious about hiring counsel to help in this, and if this is in SoCal courts, feel free to contact me. Ill be happy to help use whatever defenses there may be. Keep in mind a little free advice: When arrested for DUI, whether alcohol or drugs, then upon release from jail or booking the defendant is given documents that include a notice that you have only ten days to file a request with DMV for a hearing on an appeal of an automatic one-year suspension of your license imposed by DMV. That is separate and runs consecutively with any suspension that may be imposed by the court. Contact DMV and do so, timely, then appear at your scheduled DMV appeal hearing and present any supporting evidence and testimony.

The tests are designed to be accurate within a certain range - but many people dispute that. If you talk to a lawyer, they may feel it best to hire an expert that can talk about the breath test and it's accuracy, or not, to help at trial.

It is not accurate at all. Scientists including toxicologists and others can tell you that the breath machines used most frequently are bogus. However, to introduce the proper evidence through the correct experts costs about $5,000. Unfortunately, the legislature has adopted legislation that allows the test results as prima facie evidence of intoxication, requiring a defendant to affirmatively prove otherwise.

Relatively accurate. Yes, you can fight its accuracy.

There are many ways in which a BrAC test can be attacked. Some ways attack the machine itself, the maintenance procedures, the officer's training, how the officer conducted the test that night, and the particulars of the accused. Do not just give up because the officer says you were impaired or the test produced a particular result. You should hire a DUI attorney ASAP.

You certainly must fight this matter. There are many variables that must be dealt before such a test is considered valid. A DUI is very serious and has lasting consequences. A .08 BAC should always be reviewed by an attorney.

Breath tests can be relatively accurate so by inference than can be inaccurate. The accuracy depends on so many variables but one of those variables is the "confidence interval." If your BAC is exactly 0.080 then it is very possible that it could be comfortable less than that number. However, the toxicology laboratory would testify using the "mean" of both numbers from the BAC test. It is complicated but it's highly likely your BAC was less than 0.080. Talk to an attorney.

Accurate enough for the state but it's funny you ask. The state is switching over to a supposedly more accurate breath test instrument manufactured by Dreager in Germany. In fact, most prosecutors will cut you a break on a first-time DUI with a Breath-alcohol concentration (BAC) of .08. They would probably offer you a reduced charge of Negligent Driving in the First Degree. To be guilty of that you just have to have driving that is negligent and showing signs of having consumed alcohol. That charge would not result in your license being suspended but you're not out of the woods yet. The Washington Department of Licensing (DOL) has the right to suspend your license for having a BAC above .08. However, you have the right to a hearing on the matter. It is of the utmost importance that you send in your paperwork with a check for $200. You will be notified of a telephonic hearing date and time. If you can't afford $200, you can petition to have the fee waived. The paperwork the officer should have given you. Now, probably the most important thing here is to retain an attorney who is experienced in representing people for DUI before you have the telephonic hearing. The breath-testing instrument is a precise but fallible device. A competent attorney will review the instruments repair and maintenance records and interview the arresting officer and witnesses before the hearing. It takes a moderate amount of knowledge of Physics and Chemistry to interpret the records so chose an attorney carefully.

All DUI's can and should be aggressively fought. Just because there is a breath test reading of .08 or more does not mean there is sufficient evidence to convict. The breath test may not be accurate, it may be affected by other substances, it may not be admissible in court for any number of legal reasons. Even with a breath test, there are numerous other legal and factual issues to be raised that could result in reduction or dismissal of the charge.

Yes! Regards,

Was it .08 or just over .08 ? The general rule for most breath tests is that there is a .02 margin of error. So if your test is in the range of .10 to .08, you can usually fight the case, depending also on the facts of the driving, arrest, testing, and drinking. How do you know if the test is accurate? You dont. You can tell if the test is consistent because they take at least two samples, but you cant KNOW for sure that its accurate. The jury must put their faith in the machine.

The DUI breath test is not always accurate. How the test is performed is as important as the reliability of the equipment being used to complete the tests. I use experts to evaluate the quality of the test performance and results before proceeding to trial or deciding to enter a plea. However, there are other issues to consider besides the test itself, such as whether there was a reasonable suspicion to stop the driver. Was there probable cause to arrest? Because the consequences of a DUI are so severe, it is worth having your case evaluated by an experienced lawyer to determine your next steps. Also, if you have not sent in your 10 day letter to appeal the automatic license suspension, you should do so immediately.

Specifically, breath test machines must be properly calibrated and checked frequently in order to maintain accuracy. If the technician working on the breathalyzer missed calibration by a small amount, the testing for that device will be incorrect. Likewise, the breath test is a method to gauge blood alcohol levels (BAC) at the time of driving. Therefore, a breath test given two hours after driving will not accurately show the driver's BAC or alcohol levels at the time of driving. Only after several mathematical calculations can a lab technician attempt to ballpark the alcohol levels at the time of driving based on the breath test.

You'll have to hire an attorney. Then your attorney should know what documents to subpoena in order to check the accuracy of the breath test. Beyond that though, you may have a good case for a "rising BAC" defense. Consult some attorneys. They will be able to go into more detail. Feel free to look up my contact info and call me directly if you wish.

That depends if any defense exists.

There is a margin of error (variance) and you can fight it. Particularly if it is within 02 of the 08. Call for a consultation.

All breath machines have a margin of error that we can attack. I have been able to help a great number of clients with tests like the one you describe!

Yes. There is a chance. If you hire an expert they can find an error of margin of plus or minus 0.03% BAC.

A blodd test is much more accurate. You have a right to ask for a blood test if you take their test first, The breath test is based on a ratio of alcohol to deep lung air as it relates to the blood alcohol ratio. This varies from individual to invidual. The average is built into the machine and the actual reading can be higher or lower. You need an attorney.

There is absolutely a chance to fight and to win. Remember, that test - even if accurate - measured your breath at the time it was administered and not at the time you were driving. Moreover, many people walk on cases with such a low result. You should consult with a lawyer ASAP because there are other issues involved, too, including the driver's license revocation hearing which must be requested within 15 days of your arrest.

The machines are calibrated by the State. You would be able to obtain this information through criminal discovery.

Absolutely fight this. You have an excellent chance of getting the charges reduced. A lot depends on what you told the cop. If you told him you just finished your last drink a few moments ago, that is good. It means the booze was not yet in your system at the time you were driving. If you said it was several hours ago, that is bad. It shows you were actually higher than .08 at the time of driving. Either way, take the advice of an attorney who has seen the police report. Do NOT go straight to court and plead guilty. As to the accuracy, you need to see the machine records but the rule of thumb is ten percent either way.

You can fight that. The machine can be proven inaccurate. You need to retain a good criminal defense attorney who handles DWI cases. Unless you are in a county where the DA has a no plea policy on DWI cases, you will likely be offered the impaired, which is not a crime. Even if you "fight" the case and go to trial, the best you might do is an impaired. If you are in a no plea county, you may want to go to trial to try and avoid having a criminal record. I am a former federal and State prosecutor and now handle criminal defense and DWI so please feel free to check out my web site and contact me if you wish to retain counsel.