• Breath Tests


    When you are suspected of DWI, technology can play a role in whether or not you are charged -- and the misuse of technology can be the difference between a wrongful conviction and walking away with a clean record. 

    There is a lot of scientific principles that come into play when it comes to breathalyzer tests. These tests use highly complicated technologies to detect tiny molecules of alcohol in a driver's breath . . . and this testing isn't conducted by a scientist, or in a laboratory. It's administered by the police, with minimal training regarding what they are doing, and its done in a dirty police station, jail, or even out of the trunk of a squad car. At any point, either the way the test is administered or the technology itself can fail and that can affect the result that is given. That means a person can be charged when they are innocent or the charges could be exaggerated in some way, causing them to be more serious than the offense was. 

    There are many factors that come into play when determining whether or not a person is intoxicated. DWI charges are typically based on the amount of alcohol in a person’s blood (or breath, or urine). Blood tests are the "gold standard" when it comes to alcohol testing, and urine tests are the "black sheep" test that is rarely used (at least for alcohol). But breath testing is not only the most inaccurate type of testing, and the one most prone to error, but it is also the most commonly used test in Minnesota. If you were arrested for DWI, the odds are high that you submitted to a breath test.  

    But can you trust that number? It depends on a lot of factors, including how the test was administered, how well the machine was calibrated, and how accurate the result actually is. 


    Minnesota currently uses the DataMaster DMT to test for breath alcohol. The old machine, the Intoxilyzer 5000EN, had it's own problems, but this "new" machine is inferior to the machine it replaced in many ways. And many of the problems with the old machine still plague the new one.

    How a breath test is administered matters -- a lot. Law enforcement MUST conduct at least a fifteen minute observation period to ensure that drivers do not burp, belch, or vomit (it happens) prior to the breath test. That's to prevent the sample being contaminated by "mouth alcohol," or alcohol vapors that don't come from the lungs, problems that will artificially increase the reported alcohol concentration.

    And even a proper observation period isn't foolproof. Drivers with heartburn or acid reflux (who are constantly "burping"), drivers who politely shield their burping from observation, drivers who are allowed to visit the restroom or otherwise leave the sight of the observing officer -- all these situations can cause serious problems with the validity, reliability, and admissibility of a breath test. And these situations happen a lot, even if the driver doesn't remember them happening. You'd be surprised how many cases we win just by watching the video recording of the observation period and seeing a huge red flag pop up. 

    Or think about this: the whole time a driver is blowing in the machine, the alcohol concentration keeps going up (trust us, it does). Why do you think the officer is hovering nearby, chanting "blow, blow, blow, blow harder, BLOW!!!" That officer has one eye on a little screen that shows the driver's alcohol concentration, and you can bet he's watching to see if and when it crosses the legal limit. A driver only needs to provide 1.5 liters of breath for a valid breath sample, yet most of our clients blow 2 liters, 3 liters, sometimes 4 or even 5 liters. On some of those tests, we can actually calculate what their alcohol concentration would have been if they had stopped blowing once they reached 1.5 liters -- and many times, it would have been well below the legal limit. Does that sound like test manipulation to you, because it does to us.

    Problems with the observation period, or the administration of the test, make the entire breath test result suspect. At that point, its garbage going into the machine, so what's coming out should be treated like the garbage that it is. And garbage shouldn't be used to convict anyone.


    If you were sitting on an airplane, ready to depart, and the pilot suddenly announced that one of the engines was reporting an error, what would you expect? Would you want the pilot to return to the gate and call for the mechanics, or just try to take off anyway and see if the error keeps happening?

    Unless you have a death wish, you'd want to get on a new plane. But when the DMT reports an error, it's typical for the officer administering the test to just try and do it over again. And again. And again. Until they either get a result that isn't flagged with an error, or they decide to charge the driver with "refusing to submit to testing" (that happens!). 

    Challenging a breath test involves more than just looking at the final result. We look at the maintenance logs for the machine (this complicated piece of machinery gets a tune up once a year, whether it needs it or not . . .) and the logs for all previous tests. Sometimes we win cases just by noticing the amount of errors that went on BEFORE our client ever saw the machine. Other times we have a firm record of just how many errors happened during our client's test. 

    We can also see if a machine is biased in one way or another -- either reading "too high" or "too low." Sometimes that doesn't matter, but if someone is close to the legal limit, it matters more than anything else in the world. 


    When the legal limit is 0.08, and the penalties dramatically increase at 0.16, "close enough for government work" simply isn't close enough after all. The difference between 0.079 and 0.080, or 0.159 and 0.160 is enormous, and the accuracy of a breath test is incredibly important.

    When we were selected as Attorneys of the Year in 2016, it was for our work unmasking the inaccuracies of the DataMaster DMT. Even when the test is administered perfectly, and assuming the machine was perfectly calibrated and maintained, the amount of error that affects breath tests in Minnesota is enormous. Check out these numbers, which are all based on data released by the Minnesota BCA and apply to Minnesota's fleet of DataMaster DMTs:

    If someone's average breath alcohol concentration was 0.180, their ACTUAL alcohol concentration could have been as low as 0.148!

    If someone's average breath alcohol concentration was 0.095, their ACTUAL alcohol concentration could have been as low as 0.782!

    If someone tested right on the edge at 0.080, their ACTUAL alcohol concentration could have been as low as 0.065!

    That's a huge spread of potential values, which isn't surprising because breath alcohol measurements are very inaccurate. But when those numbers are the difference between jail, or a vehicle forfeiture, or losing your Commercial Driver's License, you need to know just how (in)accurate a breath test is. 


    Decades ago, we set out to make sure that we kept the government accountable when it comes to prosecuting DWIs. That naturally meant learning more about breath alcohol testing than the government agents who conduct the tests. Along the way, we've racked up a lot of experience -- from joining the American Academy of Forensic Scientists, to becoming faculty for the National College for DUI Defense, to founding the DUI Defense Lawyers Association, and more

    We've been to the manufacturing plant that builds DataMaster DMTs for Minnesota; we've spent days reviewing documents deep in the heart of the Minnesota Bureau of Criminal Apprehension; we know every document related to this machine like we wrote them ourselves, and have read more peer-reviewed documents on breath alcohol testing than you ever knew existed. And we do it all because we know from first-hand experience that this is what it takes to get results for our clients