Don’t Trust the Breathalyzer

I have people call me every day and ask, “If I blew over the limit…..how can I win my case?”  People just can’t imagine that they could blow over the limit and NOT get a DUI conviction.    The very first step in building a defense in a case with a breath test over the legal limit is to explain why I don’t trust the breathalyzer.    Some jurors literally think it’s their job to listen to the evidence waiting for that magic number from the breathalyzer, and if it’s over the limit they are ready to return a guilty verdict.   If the jury isn’t properly educated about why the prevailing science tells us don’t trust the breathalyzer, then the jury will accept the breathalyzer as accurate.

I have personally used this defense to have many DUI charges dismissed in court and at the DMV for my clients in my California DUI defense practice.  One of the most effective defenses to present in a California DUI case is the simple fact the breathalyzers are far from perfect.  Jurors and Judges must be educated about the flaws these devices suffer from.   When returning a verdict, don’t trust the breathalyzer!

Can a breathalyzer measure your blood alcohol content?

The first step in the analysis is to accept that the breathalyzer is not actually measuring your blood alcohol content.   The breathalyzer is taking a BREATH sample, not a BLOOD sample.   So a breathalyzer device, even if operated 100% correctly, under perfect testing conditions, and in perfect maintenance and calibration, will never yield your blood alcohol content.   If we really want to know what’s in someone’s blood, blood is the only place to look.    This is the starting point for why I don’t trust the breathalyzer.   What the breathalyzer will yield is a Breath Alcohol Concentration.  This is sometimes referred to in California courts and California DUI law as a BrAC.   This should be your first clue ….don’t trust the breathalyzer!

How Does the Breathalyzer Work?

Why do we test people’s breath to determine the level of intoxication or impairment?  Does the amount or stench of alcohol on your breath actually help determine how drunk you are?  Definitely not.  For example, someone could stink like a brewery after drinking a six pack of non alcoholic beer.   That person is obviously not impaired, but they sure smell like it.   On the other end let’s take someone who had half a bottle of vodka, some breath mints and shower.  They smell great, but they should call a cab.  So why take a breath test?

The basic scientific principle comes from something called Henry’s law.  Henry’s law says that in a closed system, the amount of ethanol in the airspace above a liquid is proportional to the amount of ethanol in the liquid.   “Closed system” implies that this is taking place in controlled environment.  I’m a lawyer not a chemist, so I’m going to butcher Henry’s law for purposes of explanation.   The basic idea is that we can use the air above the alcohol in your body to determine how much alcohol is in your blood.    The problem with applying Henry’s law to Breathalyzer tests for alleged DUI drivers is that in order for the formula to work, we need a closed system.  Testing on the side of the road, in the middle of the night, based on the breath exhaled by someone scared shitless standing next to a guy with a gun is not a closed system.  But that’s another blog post for another day.  Let’s assume the system is closed and move to the actual flaws in the machine that tell us….don’t trust the breathalyzer.

Partition Ratios – Don’t trust the breathalyzer

Partition Ratios are just one of the many reasons that I don’t trust the breathalyzer.    Using partition ratios to win your DUI case starts with understanding how the breathalyzer generates a number from the breath sample.   The breathalyzer measures the amount of alcohol in your BREATH and then does some math.   When doing this math, one of the basic assumptions made by the software in the breathalyzer device is that the partition ratio for the subject is 2100:1.   So the breathalyzer ASSUMES that the conditions inside the body of the person blowing into the machine will create an environment in which 210 liters of breath contains the same amount of alcohol as 100 milliliters of blood.   So essentially, the breathalyzer will take a reading of you Breath Alcohol Content and multiply it by 2100 in order to give your Blood Alcohol Content.

Using the partition ratio to win your case

The key to this defense is that the partition ratio of 2100:1 is simply an average for human subjects.   Actual testing in scientific studies has shown that people can have a partition ratio of anywhere from as low as 834:1 and as high as 3005:1.   Why does this matter?   Well as much as I hate to admit it, it’s time to do some math.   Let’s take an example of a subject with a breathalyzer test result of .10.   This person is obviously way over the legal limit right?  Maybe not.   Remember that this test result of .10 is based on the breathalyzers assumption that the subject has a partition ratio of 2100:1,   What if scientific testing were to show that our subject actually had a partition ratio of 834:1?  Or what if we had 3005:1?  If our subject truly had a partition ratio of 834:1, the breathalyzer would still read a .10 (because the software ALWAYS uses this number), but our subject’s true blood alcohol content would be .03.  Less than HALF of the legal limit in California.   If our subject truly had a partition ratio of 3005:1, the breathalyzer would still read a .10, but our subject’s true blood alcohol content would be .14   You may need to go back and read this a few times for it to sink in but the breathalyzer showing someone is well over the legal limit, is actually telling us that the person is somewhere between a .03 and .14 depending on their actual partition ratio.

Partition Ratio Defense – So Effective it’s Illegal

DUI defenses that work are not popular with the prosecutors, Judges, MADD advocates, and other government types.   So when confronted with science that challenges the validity of a DUI conviction, they do exactly what you would expect, they change the law.  In California, VC 23152(b) has written it right into the law.   The legislature has determined that we don’t care what your partition ratio really is, because in this here state not only is it illegal to drive with a blood alcohol content of .08 or greater, it’s also illegal to drive with a breath alcohol content of .08 or greater assuming a partition ratio of 2100:1.   This means that the legal limit is not really .08 for all people driving in California.   Depending on your partition ratio, your number could be as low as .03 and you could be found guilty under the law in VC 23152(b).   Now before you go running off to plead guilty, keep in mind that partition ratios are still completely admissible and relevant as a defense to VC 23152(a), and more importantly, partition ratios are just one of many reasons that I don’t trust the breathalyzer.   Properly defending a DUI charge requires use of multiple strategies, not just one.  To learn more about how to properly defend a DUI charge give me a ring at 800-797-8406 or send me an email using attorneygallagher@gmail.com.  Visit our website by clicking here.  You can also check us out on YELP.