Can Blood in the Mouth After an Accident Affect the Breathalyzer?

Top Torrance Criminal Lawyer
Matthew Ruff, Torrance Criminal Defense Attorney

It is not uncommon in some DUI accident cases for the driver to sustain injury to their face from the deployment of the airbag. The force of the bag hitting the facial area can be quite substantial causing cuts to the cheeks and sometimes cuts to the inside of a person’s mouth, gums and lips. Quite often these injuries are not severe enough to require medical attention. When the cut is serious enough to leak blood into the mouth these types of injuries can cause problems with the breath machine, here’s why.

Breath testing in drunk driving cases involves the collection of a sample of breath from the suspected impaired driver for the purpose of determining the ethanol content in their blood. In order to determine a person’s BAC level the machine is designed to capture a sample of deep lung air that originates from the subject’s alveolar region of the lungs. The theory behind this is that the alveolar air contains molecular levels of ethanol which can be extrapolated to determine their blood level by using a partition ratio of 2100 to 1. This extrapolation takes place inside the machine whereby the device literally multiplies the alcohol molecules 2100 times and reports it as a concentration of BAC. For example, .08% which is the legal limit in California. Alveolar refers to the smallest air sacs in the lungs and to that portion of the expired breath which is in equilibrium with respect to alcohol with the immediately adjacent pulmonary blood. In California a breath alcohol concentration shall be converted to an equivalent blood alcohol concentration by a calculation based on the relationship: the amount of alcohol in 2,100 milliliters of alveolar breath is equivalent to the amount of alcohol in 1 milliliter of blood.

With regard to the issue at hand, imagine a person who may have had a small amount to drink and subsequently that alcohol gets absorbed in the body and makes its way to the bloodstream. If the drinks were minimal, say a couple beers, the person’s BAC or blood alcohol level will be relatively low such as .03-.05 which is not above the legal limit. However, now assume that person gets in a collision and their lip is busted from the airbag explosion. Now lets further imagine they are arrested for driving under the influence because the officer smells the alcohol on their breath and they are off balance due to the impact of the accident. That person chooses a breath test and blows into the machine while small amounts of blood are leaking into the mouth.

The sample collected contains the alcohol in his blood which gets converted into a ”breath air” concentration by multiplying it 2100 times. This molecular level of alcohol in his blood now fools the breathalyzer into thinking it was alveolar air but it was not. As a result the reported concentration is now inflated artificially resulting in a false high level of BAC. Experts in the field have stated the problem this way: “the increase in alcohol molecules caused by blood leaking inside the mouth disrupts the equilibrium upon which the breath test is based and will thus lead to “overreported” results” (See People v. Ernsting, 2018 IL App (5th) 160330).

When a subject has fresh blood in his or her mouth and that blood contains even low levels of alcohol, the results of the breath test is not reliable within a reasonable degree of scientific certainty. The problem of mouth blood that contains molecular levels of ethanol is that it also arguably violates Title 17 which governs breath testing in the state. Most DUI Attorneys agree that if the sample collected is contaminated by sources that do not originate from the deep recesses of the lungs then the sample is not ”essentially alveolar air” which is what the Regulations require. Moreover, some states prohibit ”foreign substances” in the mouth during the testing process, in many of those states blood in the mouth qualifies as a foreign substance so as to invalidate the results.

If you or someone you know has been in an accident, sustained a mouth area injury and was charged with DUI and believe the breath test was wrong, call Torrance Criminal Defense Attorney Matthew Ruff for a consultation and discussion about your case.

About thetorranceattorney

Matthew Ruff is a Torrance criminal defense attorney located near the 405 freeway on Crenshaw Blvd. Focusing on DUI and serious criminal cases for over twenty five years. In addition to criminal cases, Matthew also defends clients at the DMV regarding license suspension hearings stemming from drunk driving arrests.
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