During the 2003 season of Mythbusters, hosts Adam Savage and Jamie Hyneman attempt to beat a breath test.  From a DUI lawyer’s perspective, this episode is funny because it reveals a number of flaws that an unsuspecting person might not detect.

Initially, it is important to understand that the Mythbusters were attempting to use various substances and objects to create a lower breath score.  The best example of this myth is placing a penny in the mouth before blowing.  Supposedly, the cooper in a penny will create a chemical reaction that will reduce the alcohol reading or create an unstable result due to a small electrical current generated by the cooper.  The trick doesn’t work at all, and Mythbusters explored this on the show.

Myth busted, right?  Right.

But there are several problems revealed during the course of the Mythbuster’s show.  First, Adam slams down 5 scotches and clearly admits that he feels intoxicated.  He proceeds to blow a .03, describing himself as a cheap date.  Later during the show, the announcer indicates that “breath tests work because alcohol is carried by the blood into the lungs and exhaled.  The amount of alcohol on the person’s breath is proportional to the amount in their bloodstream.” Unfortunately, Adam’s BAC (blood alcohol concentration) was likely not a .03.  Because Adam drank a number of drinks in rapid succession, he was feeling the alcohol, but it had not become fully metabolized.  Alcohol is absorbed through the stomach and small intestine, where it is then distributed to other areas of the body through the bloodstream.  Adam was feeling the alcohol in his brain, but only a small amount of alcohol had reached the stage where it is eliminated from the body.  His breath score was lower than his blood might have revealed.  If Adam had stopped drinking and tested again later after he was fully post-absorbive, he might have scored much higher.

The announcer’s declaration that “the amount of alcohol on the person’s breath is proportional to the amount in their bloodstream” is obviously misleading in Adam’s .03 score, but the misleading nature of this statement is problematic.  The proportional nature of breath-to-blood requires a conversion factor.  The conversion factor is set arbitrarily by law even though everyone has a different breath-to-blood proportion.  Approximately 20% of people blow higher than the amount in their blood.  In extreme cases, this conversion factor can make a .02 appear to be a .08, and .06 translates into a whopping .25.

During Adam’s next breath test, he scores .11, but this test is hardly a reliable result.  Viewers watch Adam place his scotch on top of the breath machine.  If Adam had a sip of that beverage within 15 or 20 minutes of blowing, the machine should have detected mouth alcohol or produced an extremely high score.  A single sip of regular beer will drive the numbers up into the .20 range.  The machine is supposed to detect this, however, and prosecutor frequently tell jurors to believe that the machine’s reading is reliable because of this programming.  It is known as the “slop detector” system.  The name is a little misleading because there is no physical device inside the machine.  The machine calculates the alcohol in rapid succession, approximately four times per second.  As it makes these calculations, an “alcohol curve” should appear that rapidly rises and plateaus.  The plateau is assumed to be the person’s BrAC (breath alcohol concentration).  If a negative value is detected during the assumed plateau, this indicates an unstable result or a spike in the alcohol reading.  A negative value should be rejected by the slope detector because it may indicate the presence of mouth alcohol.

The announcer then moves on to show how Adam and Jamie cannot pass field sobriety tests.  On the first test, the Walk and Turn (WAT) Test, the officer interrupts Adam during the test saying, “Ok now stop! I want you turn around just on the balls of your feet.”  If you’re stone cold sober, try this at home alone.  You will look like an idiot trying to perform this silly version of the test.  The oral instructions for the WAT are very detailed, and regarding the turn, an officer is trained to state, “When you turn, keep your front foot on the line, and turn by taking a series of small steps with the other foot, like this. (Demonstrate.) ”

The next two tests that the officer has Adam and Jamie perform are the finger to nose test and the Romberg evaluation (standing with eyes closed and head tilted).  Both of these tests were rejected by the National Highway Traffic Safety Administration because they were unreliable.  If either Adam or Jamie were drunk while performing these two tests, they didn’t appear to have problems passing those tests.

Mythbusters proceed back to the police station to perform more breath tests at this point.  The pair experiment with breath mints and an onion.  While these might mask the odor of an alcoholic beverage from the human sense of smell, these substances cannot reduce the amount of alcohol in a person’s breath from a breath machine.  Certain cough drops, however, can add menthol to a person’s breath, which might increase the apparent alcohol reading.  Menthol is part of the alcohol family.  In September 2005, German police warned motorists that “sucking a fisherman’s friend could get you into trouble.”  A German motorist was arrested but blood testing later revealed he was actually 0.00 BAC.  They found that eating just three of these cough drops could produce a BrAC of .24.

Another substance that Mythbusters experiment with are dentures with a denture adhesive.  Now, no one has ever argued that dentures reduce the BrAC, but they include this in the experiment because several people have indicated that it may increase the apparent BrAC.  Lo and behold, Adam produces a higher result than he did mere minutes prior!  This seems particularly troublesome, since these little deviations could be the difference between guilt and innocence.

Finally, Adam tries a mouth wash experiment.  Since mouth wash is mainly alcohol, it is another substance that does not appear to fit the parameters of their experiment.  If it is their desire to reduce the BrAC, why are they using mouthwash?  Nonetheless, Adam swigs a little mouthwash and blows into the machine, which produces a .43 alcohol reading.  If poor Adam were under arrest, the jury would be appalled to hear he was so drunk.  But again, the slope detector system ensured that it wasn’t mouth alcohol, right?  Not to worry, they explain, “to iron out glitches” the police “always test you twice.”  This is frankly not true.  A single test is enough for a prosecutor to get a conviction, and the accused is left to argue about the “glitches.”