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Can evidence of a false breathalyzer result help me if I’ve already been convicted?

On Behalf of | May 28, 2021 | OUI Defense

Breathalyzer tests have long been viewed as the gold standard for determining driver intoxication. In a courtroom setting, a breathalyzer result showing a blood alcohol content (BAC) above the legal limit can be difficult to dispute. Such evidence can make a jury likely to convict.

But are breathalyzer machines as foolproof as we imagine? New research shows that certain breathalyzer machines are more prone to error than others. The device used by Massachusetts police between 2011 and 2019 – called the Draeger Alcotest 9510 – has a particularly high rate of false results.

What makes this breathalyzer unreliable?

There are two main failings of this breathalyzer machine:

  • Variable human temperature: The breathalyzer’s testing is based off of the average human’s breath temperature – which is 34 degrees centigrade. However, humans are not homogenous, and neither is their breath temperature. If a suspect being tested has a breath temperature of just one degree above average, it can throw off the test results by up to 6%.
  • Equipment degradation: Another huge failing of the Alcotest 9510 is that one of the machine’s sensors – a fuel cell which measures the electrical current of the breath – becomes less and less accurate with repeated use. This means that the results of the 100th person tested on the machine will be less accurate than those of the first, and the 1000th person will have even more skewed results.

Reversing your conviction

Since the failings of the Alcotest 9510 have come to light, Massachusetts police have stopped using this machine. However, there are an estimated 27,000 Massachusetts residents who were convicted of operating under the influence (OUI) based on this device’s readings.

If you were convicted of OUI between June of 2011 and April 18 of 2019, you may have grounds to challenge your ruling if either of the following is true:

  • You admitted to insufficient facts
  • You pled guilty

Don’t let a false breathalyzer reading obstruct the rest of your future. Consulting with an experienced OUI lawyer can help you get a clean slate.


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