As experienced Rochester DWI lawyers, we have seen a number of changes to the technology used in breath test machines over the years.

To obtain a breath test result that properly reflects blood alcohol content, it is important that the air tested be what is referred to as “deep lung air” – air from the part of the lungs where alcohol may pass between the air and the blood – and that the sample not be contaminated by alcohol in the mouth or brought up through burping or regurgitation during the test.

In an effort to address these issues, many of the newer breath test machines that use infrared technology to measure alcohol content have a slope detector.

Unlike older machines or machines that use other technology to measure blood alcohol content, many infrared machines are capable of repeatedly measuring the amount of alcohol present in the sample as it is being delivered, which is necessary for the slope detector to work.

Under ideal conditions, a person with alcohol in their system should provide a breath sample that steadily increases in alcohol content as air from deeper within the lungs is breathed out.

The slope detector measures the rate of change in the sample against what has been programmed into it as normal parameters.

If it detects anything that would constitute an aberration from what is considered a normal rate of change – such as a decrease instead of an increase or a sudden spike in the alcohol content – it will determine that the breath sample being provided is not a valid sample of deep lung air.

This will usually result in the breath test being terminated based on an invalid result.

A driver who has taken the breath test needs an experienced DWI lawyer who understands how the breath test machine works.

If you have been arrested for drinking and driving, call us at 585-484-7432 for legal help.