Drunk Driving and Personal Breathalyzers

Posted on Tuesday 23 October 2007

Recently, some companies have come out with personal breathalyzers. People are supposed to buy these small, portable, battery-powered devices so they can find out whether they’ve had too much to drink or not. Will using a personal portable breathalyzer help reduce drunk driving? No, I actually think it may make things worse. Personally, I think this is a very, very bad idea. Here’s why…

The Reasons

First, a personal breathalyzer may not be all that accurate. It is more than likely that the accuracy of a mass-produced, cheap consumer unit isn’t going to be all that high. They could be affected by improper usage, miscalibration, or factory quality control issues. Another problem is that any reading taken by a portable unit only reflects the alcohol present in the blood at the time of the reading, but may not accurately reflect all the alcohol consumed by the user—depending on their drinking habits—it may be actually be significantly lower than what their true alcohol content will be when all the alcohol is absorbed.

Second, a breathalyzer reading doesn’t really accurately represent how drunk or incapacitated a person necessarily is at the time. I know some people are less affected by alcohol, due to their size, environmental conditions, what they’ve eaten, genetic factors and drinking experience. I know other people, who will be more greatly affected by even small amounts of alcohol, due to those same factors.

Third, a personal breathalyzer reading indicating that the user isn’t above the legal limit may give a person who is too drunk a false sense of confidence about their to drive, even if they would normally have doubts and err on the side of not driving. This may lead to more drunk driving accidents and result in more drunk driving fatalities.

Finally, any breathalyzer, even the more accurate full-size units that are carefully calibrated, is only going to tell the user what their blood alcohol content is at any specific point in time. It can’t compensate for how much alcohol is in the user’s stomach. Also, breathalyzers are fairly complex devices that will generally need more maintenance and calibration than other devices, while not really accurately reflecting how incapacitated the person actually is.

The Problems

Unfortunately, many of the new drunk driving laws specifically refer to breathalyzer-based ignition interlocks. This is not an ideal way to stop a drunk driver.

The first problem is breathalyzer-based ignition interlocks are more expensive than other ignition interlocks—since they are very complex and relatively fragile electronic devices. Of course, the problem is even worse for portable devices, which are more likely to suffer physical shocks and relatively rough treatment. They may also be less robust in terms of construction due to the need to keep the unit small and light.

The second problem with breathalyzers is that they are likely to generate false positives. For instance, a person who has taken cough syrup, used mouthwash or is chewing certain types of gum could register a relatively high blood alcohol content, while their actual BAC is actually close to zero—resulting in a false positive reading.

The third problem is that breathalyzers don’t actually measure how incapacitated a person actually is—all they measure is the relative amount of alcohol a person has consumed and absorbed. One person might be under the legal limit and too “drunk” to drive, while the next person may be over the legal limit, but perfectly capable of driving.

For example, one of my good friends is a relatively heavy drinker, and he isn’t really all that affected by alcohol. He comes from a fairly long family history of alcoholics, and this has probably given him a bit better ability to metabolize alcohol. He is also a fairly large individual. Another good friend of mine is basically incapacitated by a single glass of wine. While she wouldn’t be legally drunk after a single glass of wine—she definitely wouldn’t be capable of driving safely. After a single glass of wine she has less hand-eye coordination than he does after two six-packs of beer. Of course, some of this is due to the disparity in their sizes, but the disparity isn’t that great—so some of the differences must be due to other factors.

Breathalyzers are not capable of truly detecting whether the person is actually incapacitated or not. Alcoholics may turn to other drugs if a breathalyzer-based ignition interlock is installed in their car. A breathalyzer can not detect if they are under the influence of anything other than alcohol. If the person has turned to drugs, like Valium, marijuana, or cocaine, they could be incapacitated, but the breathalyzer-based ignition interlock would still allow them to drive—effectively a false negative result.

The Solution

A non-breathalyzer based ignition interlock that actually tests the hand-eye coordination of the user is probably the best solution. The skills required in driving—hand-eye coordination and the ability to predict movement and respond to it properly—are what should be tested, not the somewhat arbitrary blood alcohol content used by most legal definitions of inebriation. Unfortunately, none of the current laws recognize the shortcomings of the breathalyzer-based ignition interlocks.

Almost 20 years ago, a electro-mechanical ignition interlock was developed. The design of the ignition interlock tests actual hand-eye coordination and the user’s ability to predict motion and react—effectively analogs of the skills that real-world driving requires.

Unfortunately, the laws in Massachusetts passed about 15 years ago didn’t recognize ignition interlocks other than the breathalyzer-based ones. Another problem is that the laws didn’t make the installation and use of an ignition interlock mandatory in all DUI cases. A lot of the political motivation not doing so can be traced back to the efforts of the lobbyists for the trial lawyers, who see drunk driving cases as a major source of income.

Generally, the laws only get seem to get tighter and more restrictive when a big media circus occurs in a tragic drunk driving case. I don’t see the laws regarding the current ignition interlocks changing anytime soon.

What can be done?

Writing your state legislators and asking them to revise the drunk driving laws to include all ignition interlocks as well as require mandatory installation and use of ignition interlocks on the cars of people convicted of a DUI charge. Finally, you should ask the legislators to require a notice on the vehicle stating that the owner of the vehicle has been convicted of DUI and implementing severe penalties for anyone who helps circumvent an ignition interlock system.

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