DUI Defender

How Roadside Breath Machines Work

Roadside breath test devices typically use an electro-chemical reaction to measure breath alcohol content. Air, from a suspect or calibration machine, is blown over a porous disc. This disc is a wafer of materials, one of which will react with the alcohol, freeing electrons and causing a small electrical current. This current is measured and then translated in to an alleged Breath alcohol content.

In order to ensure a “good” breath sample, the devices measure the flow time of the air sample and “capture” a sample near the end of the “average” persons breath. Some devices are also equipped to allow a “manual” capture by the officer if the flow rate and time is not met. This is done by the simple pushing of a button.

Typically in breath testing, not all of a person’s breath is tested, only a small portion is reviewed. This is done by a simple piston popping closed once blow time or manual trapping has occurred. This sample is then analyzed and the results displayed.

Problems with Roadside Breath Machines
Because these devices only sample the air stream, they can easily end of measuring mouth alcohol instead of true breath (also known as deep lung alcohol). Laboratory machines typically have a “slope detector” that allows a trained operator to distinguish between the two. With a slope detector there is constant monitoring of the breath as it passes through the sample chamber and an evaluation made. Any rapid falling off of the alcohol level, or “slope”, triggers the sensor to indicate mouth alcohol.

Next, these machines are subject to more calibration problems. Unlike their big brothers, these machines are not being kept and maintained by laboratories and their staff. Most are housed by local cops or CHP. The maintenance, or more appropriately, calibration is being done by police officers with no scientific back ground.

Depending on the underlying technology, some roadside breath analyzers might be subject to other serious problems. For example, with fuel cell devices there is a lack of specificity: the devices will detect a large number of chemical compounds, indiscriminately “reading” them as ethanol. Although the manufacturers of the passive alcohol sensor claim in their advertisements that it “is unaffected by acetone, paint and glue fumes, foods, confectionery, methane and practically any other substance likely to be found in the breath,” the fact remains that any device using fuel cell oxidation is not specific for ethanol; the manufacturer’s use of the term “practically” should certainly create suspicion.

There has been a lot of discussion recently regarding diet and alcohol. Some in the medical community have documented the fact that diabetics can enter a state of ketosis wherein their breath will test positive for alcohol on many types of breath analyzers that have specificity issues (devices that are not alcohol specific). In a recent Swedish study researchers found that low calorie diets can result in false positives that prevent ignition interlock devices from allowing cars to start. If the devices can’t tell the difference between ethyl alcohol, ketones and isopropyl alcohol, how can we trust the results of blood alcohol measurements made by similar machines used in law enforcement?

A bill is currently working its way through the California State Legislature (Senate Bill 177) that will require every person found guilty of DUI to install an ignition interlock device on their car.

Ignition Interlock Device-

An ignition interlock device is a machine that is installed in a car between the key and the starter.  The driver must blow into the device prior to the car starting.  If the machine determines that the driver is not “sober” it will not start.  These devices also require periodic testing of the driver, meaning that while the car is on the road the driver must blow into the device.  In the event that the vehicle detects alcohol, it initiates an alarm, the lights and horn will sound until the vehicle is shut off, it does not shut off the engine immediately.

Why this is bad-

The number one reason cited by MADD and the proponents of this change in the law is the increased rate of repeat DUI’s.  The statistic most recently cited by the proponents of this law (who include the lobby group for the manufacturer’s of these devices) includes all of the new repeat offenders added to the statistic since the “look back” period was changed from seven years to ten thereby increasing (by at least a third) the number of persons subject to inclusion in any repeat offender statistics.  The statistics in New Mexico, the only State to have a mandatory IID requirement for first offenders have been seriously manipulated to create the illusion of effectiveness.

This law will unfairly effect the working poor more significantly than the rich.  The Ignition Interlock Device must be purchased or leased from a provider.  The device must be brought in to a licensed provider every so often to have data downloaded and have its calibration verified, this too costs money.  What will the people who can not afford these devices do?  They will either sell their existing car (and purchase another car in someone else’s name), or transfer ownership to another person.  Once the title is no longer associated with the convicted driver, the Ignition Interlock is no longer required.  It doesn’t matter who’s driving the car, only to whom the car is registered.  While this will not satisfy the requirement that a device be on any car driven by the convicted driver, it is only possible to verify that any car owned by the driver has an ignition interlock installed.

The law will adversely impact the lease car industry.  The IID is hard wired into a car meaning that it must be bolted to the car, the damage caused by the installation violates the terms and conditions of most automobile leases.

The device is non-specific for alcohol.  I have had client’s who could not start their car shortly after smoking a cigarette or using mouth wash.  Many of the defenses we use to challenge criminal cases are applicable to these machines as there are no safeguards.  Some gums and other breath fresheners will cause positive measurements; again the car will not start.  The lack of specificity could result in sober people not being able to start their car to drive to work or appointments.