The Unfair Impact of Volume on Breath Alcohol

Posted On June 05, 2023 Charles Ramsay

The problem with breath alcohol testing is that it is fundamentally unfair. It’s unfair because the longer you blow into the breath machine, the higher score you get. 

The machine doesn’t take individual lung sizes into account. Instead, the final measurement depends largely on how much air you blow into the instrument.

The amount of breath a person provides into the breath machine depends on arbitrary and random variables. It depends on things like instructions from the officer, or even the subject stopping to cough mid-breath (causing less air to go into the machine).

For example, you might be testing with an officer who is trying to ensure that you blow higher than a 0.08. He wants to justify his arrest. So, he’ll encourage you to keep blowing until you reach the 0.08 mark.

Sometimes the peace officer will even cover the screen with a sheet of paper, making sure that you can’t see the numbers you’re producing. But, she’ll occasionally look at the numbers onscreen to make sure you blow over the legal limit. 

Some officers even encourage you to keep going after you’ve met the minimum volume! I’ve seen egregious examples where, once the numbers on the breath machine crossed the 0.08, the officer signaled to the subject to stop blowing.

Some officers have even admitted that they can manipulate the test results by dong this. 

What does the science say?

Take a look at the graph below. It shows that as you continue to blow, your breath alcohol concentration continues to rise. 

Image credit: Hlastala MP. Paradigm shift for the alcohol breath test. J Forensic Sci 2010; 55: 451–456.

Most breath alcohol machines require you to blow a minimum of 1.1 - 1.5 liters of air. Minnesota’s old breath machine, the Intoxilyzer 5000, only required you to blow 1.1 liters of air. 

For some reason, the state scientists decided to set a new standard for the DMT breath machine. They increased the minimum amount of air to 1.5 liters.

Did the state scientists conduct any studies to justify this change? No.

They ratcheted up the volume for no apparent reason, making it harder for citizens to provide a breath sample. 

While the breath machines have a minimum volume, they will continue to accept breath far beyond the minimum. An advanced breath machine should have a way to automatically capture a breath sample once the standard has been met. But this is not the case. The test stops when you stop blowing. 

One study showed that for every additional liter of air provided beyond the minimum volume, your breath alcohol increases by a rate of 9.2% per liter.

I’ve had some clients provide 3-4x the minimum volume. If they had stopped blowing after 1.5 liters, they would’ve had a final score of 27-36% lower.

The law prohibits arbitrary standards

The law requires that every person be treated equally. Scientific tests must be held to a high standard. The state’s breath test is arbitrary and capricious due to the fact that the test is highly influenced by the instructions the subject receives from the DMT operator as well as when the subject decides to stop blowing. 

A person who continues to blow beyond the minimum is punished with high results. On the other hand, a person who stops blowing after the minimum volume gets a lower result.

At Ramsay Law, we hold the state to a higher standard. The state needs to ensure a subject isn’t prejudiced by the arbitrary whims of the officer instructing the subject to blow well beyond the minimum volume. It needs a test that is fair for all.

If you’ve been a victim of the State’s arbitrary standards, call Ramsay Law we get results. 

Charles Ramsay