DUI in Portland: Why Does False Positive Testing Happen?

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If you’re stopped for DUI in Portland, the police may ask for a breathalyzer test. It will determine your blood alcohol content (BAC). Failing a breathalyzer test means you are over the legal limit for alcohol content in your blood, and criminal prosecution will soon follow.

But the results obtained by a breathalyzer are not always accurate, and a false positive alcohol breath test does not prevent you from getting arrested. You should hire a DUI defense attorney to represent you in a DUI case in Portland in such cases.

What Is A False Positive Breathalyzer Test?

A Breathalyzer device is used by law enforcement officials to measure the blood alcohol content (BAC) of an individual. Generally, breathalyzer tests are only precise approximately 40% of the time. The testing tools themselves have an inherent margin of error between .005 and .02% in their BAC readings.

Various factors can lead to a false positive reading by a breathalyzer test. False-positive readings mean that you will be charged with driving under the influence (DUI) without being at fault.

Factors That May Cause An Inaccurate Breathalyzer Result

Knowing the reasons for false-positive breathalyzer test results, you can file a claim against its legitimacy:

Poor Equipment Calibration

Law enforcement personnel follow precise rules to be sure that the breathalyzer tests function. The officers should service the devices used for the BAC test regularly and carefully modify them to the conditions in which they are accessible.

Errors by officers, flaws in manufacturing, or simply age may cause a device to give false results.

Plus, the portable Breathalyzer machines need consistent maintenance and upkeep to sustain their effectiveness. Without daily calibration, the device can’t work. The officers using such machines could make arrests without trustworthy evidence. These results can’t be backed up in court, often troubling innocent citizens.

Medical Conditions

Medical conditions and medications that create acid in the stomach and esophagus could result in a false positive breathalyzer test result because they increase the BAC levels and may leave some presence of alcohol in the mouth.


Some medications can also be the cause of false-positive Breathalyzer test results. Any medicine applied inside your mouth contains alcohol that can influence the accuracy of the test. If you use Anbesol to relieve gum and toothache, or over-the-counter liquids like Robitussin and Nyquil, you may blow a false positive on a portable Breathalyzer test.

It is difficult to use any nonprescription medication in the amount necessary to get drunk. But the alcohol in the mixture does stay on one’s breath for a while. The machine will detect the medication rather than your blood alcohol, and you could face the inconvenience of arrest and an impounded vehicle.

You should avoid driving while taking OTC cough and cold medicines. Other ingredients besides alcohol can cause drowsiness, also interpreted as drunkenness.

Mouth Wash

If you use a mouthwash before leaving the house, you may be setting yourself for a false positive breath test. Most mouthwash contains a pretty high amount of alcohol that can trigger a Breathalyzer machine to give inaccurate results.

Manufacturers are now creating mouthwash and fluoride rinses devoid of alcohol. But it is critical to check the ingredients of your mouthwash before buying. The breathalyzers intend to pick up on mouth alcohol. The detector doesn’t always provide an accurate result as it can also register residual alcohol in the mouth.


Breathalyzer tests can also get contaminated by outside factors like chemicals in the air. If the device is not cleaned and maintained can lead to altered test results.

Sugar Alcohol In Certain Foods

Some foods can also cause a breathalyzer to give incorrect readings. Food like pecans, ripe fruit, energy drinks, and protein bars can skew breathalyzer test results. Eating a spicy meal can also result in an inaccurate breathalyzer test.

Electronic Interference

Electronic interference from radio transmissions through police radar devices, handheld police transmitters, police station dispatchers, or even FM or AM radios can also affect roadside breath tests.

Operational And Human Error Issues

The accuracy of the breathalyzer test also depends upon the officer utilizing and maintaining the device. The human element of the test opens the door for several operational errors.

Contact Trusted DUI Attorneys In Portland

If you’ve been arrested for driving under the influence because of a false-positive breathalyzer result, you can challenge the charges. A professional attorney can help you counter any legal consequences related to the crime. The Trilogy Law Group with our highly trusted and well-versed legal team understands the nuts and bolts of DUI defense law.

We will defend your rights by all means necessary in case of a false positive breathalyzer test!

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