First Trial: 8 Million Won Fine, Second Trial: Acquittal
"Multiple Attempts Affected Breathalyzer Readings," Court Acknowledges
A court has ruled that blood alcohol concentration readings measured using a disposable mouthpiece for a breathalyzer multiple times cannot be considered reliable.
On October 7, the Cheongju District Court Criminal Appeals Division 2 (Presiding Judge Han Sangwon) overturned the original verdict, which had fined a man in his 50s, Mr. A, 8 million won for violating the Road Traffic Act (drunk driving), and acquitted him.
On August 29, 2023, at around 10:30 p.m., Mr. A was caught by police driving a passenger car under the influence of alcohol on a road in Cheongwon-gu, Cheongju. The police officer gave Mr. A bottled water to rinse his mouth and then had him blow into a disposable mouthpiece attached to a breathalyzer.
However, because Mr. A blew weakly into the mouthpiece, the blood alcohol concentration could not be properly measured, and it took 13 attempts before a reading was obtained. The blood alcohol concentration measured was 0.085%, which is above the license revocation threshold.
During the trial for drunk driving, Mr. A argued in the first trial that "it was unlawful to conduct multiple breathalyzer tests using a single disposable mouthpiece," claiming that residual alcohol in the mouthpiece could have caused the reading to be higher than it actually was. He cited the National Police Agency's traffic enforcement guidelines, which stipulate that a new disposable mouthpiece must be used for each breathalyzer test. However, the first trial court did not accept Mr. A's argument.
The first trial court stated, "The defendant merely pretended to blow into the mouthpiece 12 times and did not properly cooperate with the test," and added, "It is reasonable to interpret 'one breathalyzer test' as a case where the test is conducted according to proper procedures, except when the subject does not blow properly into the mouthpiece." The court concluded that the possibility of an inflated reading due to residual alcohol in the mouthpiece was only a theoretical or abstract doubt.
However, the appellate court reached a different conclusion. The appellate court stated, "The breathalyzer's user manual specifies that 'the mouthpiece must be discarded after a single use due to accuracy concerns,' and 'if three consecutive tests fail, wait at least five minutes and replace with a new mouthpiece before retesting.' Based on this, it can be inferred that reusing a disposable mouthpiece could result in inaccurate blood alcohol concentration readings."
The court further noted, "The defendant only pretended to blow for the first two or three attempts, but after that, he followed the police officer's instructions and blew into the mouthpiece. Given these circumstances, it is possible that, during the roughly 10 attempts where he actually blew, saliva and breath condensate may have blocked the mouthpiece's entrance, potentially affecting the breathalyzer reading."
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