As Charleston DUI lawyers, we are sometimes asked whether a person is guilty of DUI if they gave a high reading (above .08) on a breath test. The short answer to this question is “no,’ you are NOT automatically guilty. If a driver blows a 0.05% or less, then he or she can’t be convicted of driving under the influence of alcohol, although the prosecution might be able to prove the driver was under the influence of some other drug or substance. If the driver blew a 0.06 or 0.07%, then the jury is not supposed to make any inference from the reading. If the driver blew a 0.08% or higher, then the jury is instructed at the end of the trial that they may “infer” that the driver was under the influence of alcohol, but this is only an inference to be taken with all of the other evidence in the case. Also, if the driver blew a 0.08% or greater, he or she can be charged with driving with an unlawful alcohol concentration (DUAC) instead of DUI.
If our client has a reading of 0.06% or higher, we try to attack the reading, which can be done in a number of ways. Ultimately, if the case goes to trial, we try to convince the judge that the reading should not come into evidence so that the jury never hears or sees any evidence of a breath test. Before trial, during negotiations with the prosecutor, we try to convince the prosecutor that we will win on the issue of suppressing the reading from evidence in hopes that the prosecutor might recognize a weakness in their case and give a plea deal that is acceptable to our client.
Real World Example of Challenging a DUI Breath Test in South Carolina
Recently, there was a case where a client registered a 0.17% on the DMT Datamaster. Our client didn’t show signs of intoxication on the field sobriety test video, so the breathalyzer reading was the main hurdle at trial. The week before trial, Tom Nelson presented a motion to the prosecutor where he made two main arguments as to why the 0.17 reading should not be allowed into evidence at trial. First, he argued that an instruction the police officer gave to our client before the test was improper. On two occasions, the officer told the defendant “to blow as long and as hard as he can.” The owner’s manual for the Datamaster DMT provides that the machine operator to NOT tell anyone to “blow hard” into the machine. Tom also hired an expert witness in this case, a former police officer who had many years of training on the machine. The expert was prepared to testify at trial that instructing a subject to “blow hard” violates the proper operating procedures of the DMT Datamaster machine. Blowing hard can deviate from the continuous and steady flow of air the machine requires, and in this case, the subject blew a total of 2.3 liters of air into the machine, well over the 1.5 liters the machine requires. Ultimately, the expert was prepared to testify that blowing hard into the machine skewed the results. Additionally, the breath profile for the test (a graph of the air flow) showed a significant spike which reinforced his expert’s opinion. For more information on how blowing hard into a breath test machine can skew the results, please click here.
Second, Tom argued that the test results should be excluded because the officer did not give a written copy of the defendant’s rights to the defendant. The law says that this deficiency is not necessarily fatal in the context of an implied consent hearing, but Tom argued that based upon the way the statute is written, the court must suppress the breath sample at trial.
Ultimately, the prosecutor offered that our client plead guilty to lesser charge in exchange for having the DUI charge dropped, and our client accepted the offer. This recent case gives just two of many examples of how we try to suppress breathalyzer readings from evidence. Please note that results in this or any other case doesn’t necessarily mean the same or similar results in another.