Breathalyzer tests are not 100% accurate, no matter what the police or other individuals may tell you. The police have to meet certain requirements to show that the breathalyzer was working correctly before the results are admissible in court, and even if they are admissible- you can still challenge the results of the machine.
There are certain variables which can affect the results of the Breathalyzer machines. The temperature, the atmospheric pressure, the chemical composition of the alleged offender’s blood, his or her physical activity, and hyperventilation are just some of the factors that can lead to variable, and thus arguably questionable, results.
Test results can also be challenged on the basis of the circumstances of the particular testing at issue, including the skill and experience of the tester and the quality of the particular equipment used. Breath testing machines are also subject to error when the person being tested has been recently exposed to fumes, such as lacquer, paint, gasoline, or dry cleaning fluids.
Also, for the results of such test or tests to be admissible as evidence, it must be established that all tests administered were administered to the person within two hours following such person’s arrest or initial detention.
Many people wrongly assume that if they blow an above the limit reading on a Breathalyzer they are as good as convicted of drunk driving, but that is not always the case. In some cases, the results of Breathalyzer tests can be challenged on general scientific grounds, and in others, the circumstances of the particular test can be brought into question, raising a reasonable doubt about the drunk driving defendant’s guilt.