What does the status code “ambient fail” mean on the Datamaster DMT Breath Machine?

Top Torrance Criminal Lawyer
Matthew Ruff, Torrance DUI Attorney

The Datamaster DMT breath testing machine is used to determine blood alcohol concentrations of subjects arrested for DUI in Los Angeles County. The machine is used in cities such as Torrance, Redondo Beach, Palos Verdes, and most other cities in LA County except for Long Beach and the City Of Los Angeles.

The device is a “second generation” machine which replaced the Datamaster cdm machine which was used by the county for over two decades. The machine uses infrared absorption as the basis for its testing. Essentially a breath sample passes into a sample chamber of fixed volume and temperature. The chamber is essentially a cylinder approximately the size of a yellow highlighter commonly found in a office.  During the testing process a beam of infrared light passes through the chamber. When the light beam exits the chamber, it is filtered to remove undesired wavelengths. The remaining wavelengths are converted to an electrical signal directly proportional to the concentration of the alcohol in the breath sample.  The signal is commensurate to the amount of energy absorbed as it passes through the alcohol molecules in the chamber.

There are many error codes that can be generated by the machine during the breath sampling process. Among the more common is that of “ambient fail”. Sometimes the status code will be reported when the attorney reviews the usage logs and maintenance history of the machine during the discovery process.

Once the usage logs are obtained from the agency they should be thoroughly audited to determine what error messages were reported from a time period approximately 30 days before and 30 days after the test in question.

What does the error message “ambient fail” actually mean? It means the DMT was unable to establish a zero alcohol reference when measuring the air around the instrument during the initial air blank. This can be caused by a poorly ventilated room that does not allow for sufficient clearing of alcohol vapors, a breath tube pointed toward a subject, room deodorizers or hand sanitizers, etc. If possible, remove the source of ambient alcohol or move it farther away from the instrument and begin a new test with a new 15-20 minute deprivation observation period.

According to the LASD training manual, If the DataMaster DMT detects alcohol or another detectable substance in the vicinity of the instrument (ambient air) during the initial purge step in the testing sequence, the test will be aborted. Both the display and the report will indicate Ambient Fail. Operator may make notation(s) when prompted by the instrument “Any comments?” The report shall be retained by the arresting agency. The operator has the option to administer another breath test (on the same or another DataMaster DMT) or request a blood or urine sample. It is recommended that the source of the ambient fail be identified and removed from the vicinity of the DataMaster DMT before proceeding with another breath test on the same instrument.

The bottom line is this error code is telling the operator that a contaminant is present in the room and it should be removed before proceeding forward with an evidentiary test of the DUI subject.

In many cases the contamination is due to hand sanitizer in the room. If alcohol based hand sanitizer is too close to the machine it can cause this error code to display. The problem is that if the hand sanitizer is causing the machine to fail it is also likely entering the airway of the test subject and contaminating their airway and mouth cavity which could result in a false BAC measurement. Ideally the contaminant should be removed, the room should be aired out and the testing process should be started over with a new 15 minute observation period. If this is not done it can be argued the subject sample that was obtained is not scientifically reliable and violated the mandates of the California Code of Regulations Title 17.

Here is the legal argument: The alcohol molecules in the hand sanitizer that are floating around in the room ambient air get sucked up into the machine during the purge sequence and cause the test to abort. Those same alcohol molecules that got sucked in the machine also very likely got inhaled by the subject who was sitting in the same room and subsequently get absorbed in the mucus lining of the esophagus, mouth cavity and trachea. These alcohol molecules then get expelled back into the machine when the subject breathes into the breath tube, consequently causing a falsely inflated BAC reading. The sample contains alcohol molecules not originating from the alveolar region of the lungs. Without a new 15 minute deprivation period there is no way to be sure the contamination did not influence the measured results of the subject taking the test.

This situation is very analogous to when a breath test subject may burp or belch raw alcohol from his or her stomach. In this instance there is little dispute that the introduction of alcohol molecules from the stomach can falsely exaggerate BAC results, the same theory applies to an occurrence of alcohol molecules entering the airway from a contaminated ambient environment.

Matthew Ruff is a Torrance DUI Attorney with over 25 years experience fighting DWI and other alcohol related offenses.

About thetorranceattorney

Matthew Ruff is a Torrance criminal defense attorney located near the 405 freeway on Crenshaw Blvd. Focusing on DUI and serious criminal cases for over twenty five years. In addition to criminal cases, Matthew also defends clients at the DMV regarding license suspension hearings stemming from drunk driving arrests.
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