We all know that the amount of alcohol in our blood can be tested — but most of us don’t know exactly how our breath relays a BAC score. And, while we know a number of factors influence our BAC level, can certain factors skew the score a breathalyzer displays?

The truth is that breathalyzers aren’t always accurate. From the way they test to the complications that can arise during the test, here are a few reasons why.

Are there different types of breathalyzers?

Breathalyzers are devices used by authorities to measure a person’s BAC. There are many different models and grades of breathalyzers. In fact, portable breathalyzers can even be purchased for personal use. No matter the type, each one typically has a tube-like mouthpiece to blow into and a sample chamber that tests your breath.

How does your breath show the amount of alcohol in your blood?

The number that appears on the screen of a breathalyzer is an estimation of the amount of alcohol that is in your blood, depending on the amount of alcohol in your breath.

Alcohol is traceable on your breath because your blood flows through the vessels of your lungs. The ratio for this is roughly 2,100 milliliters of alcohol in your blood for every 1 milliliter of alcohol in your breath.

What factors can skew breathalyzer accuracy?

Unfortunately, there are many factors that can disrupt the accuracy of a breathalyzer test. Here are just a few examples:

  • Technology grade —Generally, breathalyzers use infrared spectrophotometer technology or electrochemical fuel-cell technology. Though fuel-cell technology is more expensive, it is also more accurate.
  • Time — the amount of time it takes your body to fully absorb the alcohol you drank affects your breathalyzer reading.
  • Chemical malfunction — Low-grade breathalyzers may confuse alcohol for simple chemical compounds in the breath caused by mouthwash, vomit, acid reflux or blood. Additionally, paint fumes in the air or plastics in your mouth can skew results.
  • Operational error — Police officers should be professionally trained to administer breathalyzer tests. However, if they fail to notice a hiccup, burp or hyperventilating, the results may not be accurate. Tests should be performed multiple times to avoid these errors.
  • System maintenance — Breathalyzers are just like any other electric device in that they occasionally glitch and require new batteries, re-calibration and keeping dry in order to function properly.

How common are breathalyzer errors?

The National Motorists Association have reported a margin of error up to 50 percent when comparing the BAC score of a breathalyzer to the results of a blood test, with a difference between 0.05 percent and 0.15 percent.

Other sources have reported a 15 percent margin of error and that 23 percent of drivers who are charged with a DUI had an inaccurate result.

What should I do if I believe my DUI charge is wrong?

If you have recently taken a breathalyzer test that didn’t seem accurate or was obtained improperly, the evidence may not be admissible in court. Consulting with a criminal defense attorney about your case can help you understand your legal options and what course of action may help you get the best outcome from your case.