The modern breath test machines used in DWI cases by all law enforcement agencies in the Rochester area are complicated devices.

They automatically perform a variety of steps related to the breath test and document the results.

When any breath test is performed on one of these machines, it should perform multiple purges during the course of the test.

Breath test machines typically perform a “purge” or “blank sample” test both before and after the driver accused of drinking and driving actually breathes into the device.

When conducting the purge, the machine is simply pulling room air into the testing chamber and performing a test to determine its alcohol content.

All such tests should result in an alcohol content score of zero.

Any result aside from zero may be indicative of a contaminant in the room air or in the machine itself that could interfere with the breath test result.

It may also indicate a problem with the functioning of the breath test machine.

The purge cycle that occurs after the driver accused of drinking and driving has provided a breath sample also is necessary because after testing the breath sample, the breath test machine will test a solution containing a known amount of alcohol to check the machine’s accuracy.

This blank sample test between the testing of the driver’s breath and the testing of the alcohol solution is necessary to ensure that no residual alcohol remains in the sample chamber that may interfere with the testing of the alcohol solution.

Again, the results of all blank sample tests should be zero.

Any result aside from zero may call into question the accuracy of the breath test result.

If you have been arrested for drinking and driving and took the breath test, we are experienced DWI lawyers who can answer your questions.

Call us at 585-484-7432 for a legal consultation.