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How Accurate is Detection and Evidence of Drugged Driving?


I’ve written long and hard over recent years about the inaccuracy and unreliability of breath alcohol and blood alcohol testing.  See, for example, How Breathalyzers Work – and Why They Don’t.

Increasingly, however, cops are confronted with a different kind of impaired driving:  driving under the influence of drugs (or under the combined influence of drugs and alcohol), also known as "drugged driving".  In almost all states, this is a criminal offense treated the same as drunk driving, even if the drugs are legally prescribed.

So how accurate and reliable is law enforcement in detecting driving impairment from drugs?  How good are crime labs at determining levels of impairment with quantitative and qualitative analysis?

Not every.

The following is part of a report from the National Highway Traffic Safety Administration of the U.S. Department of Justice.  Entitled "Priorities and Strategies for Improving the Investigation, Use of Toxicology Results, and Prosecution of Drug-Impaired Driving Cases — Findings and Recommendations" (DOT HS 810 708), the internal report paints a bleak picture not intended for public awareness. 

There is no clear correlation between blood drug concentrations and impairment for many drugs.

In DUI cases involving alcohol, a clear understanding has developed over the past 50 years regarding the relationship between increasing blood alcohol concentration and impairment. Tolerance to the effects of alcohol have been well characterized. Morever, the limitations it places on expert testimony are consistent and generally accepted by toxicologists.

The same cannot be said for drugs. The amount of research carried out is significantly more limited, and in the case of recreational drug use, researchers cannot ethically administer the doses of drugs typically taken by regular users. Other confounding factors include the common practice of combined drug or drug and alcohol use, where the interactions are not well known or understood. Additionally many drugs, particularly stimulants and narcotics, have markedly different effects in the acute phase from the later or withdrawal phases, even though the concentrations may be similar.

These limitations are a challenge. However research on this topic must continue and should be supported by laboratories, universities, drug companies, and funding agencies. This area of research is currently neglected. Because of these limitations, standard approaches to DUI prosecution that work well for alcohol, where there is a known relationship between alcohol concentration and impairment, may not be the optimum approach for DUID. Alternatives such as drug per se statutes, particularly for illicit drugs that are illegal in all circumstances, should be considered.


Does that last sentence sound familiar?  Years ago, the Feds put pressure on the states to adopt new DUI laws:  drunk driving per se statutes.  Since accurately detecting alcohol impairment was often difficult, the "driving under the influence" or "driving while impaired" laws were supplemented by a so-called per se law: it was illegal per se (in and of itself) to drive with a blood-alcohol level of .10%.  With intense pressure from MADD, this was later lowered to .08%.  

Thus, if a citizen were suspected of drunk driving and was tested at above .08%, in most states he would be charged with both crimes — DUI and the per se offense — and could even be convicted of both.  It did not matter whether or not he was "drunk" or his ability to drive was impaired.

The whole point of the per se laws is to avoid the difficulties of proving a driver was impaired.  Impaired ability to drive is no longer relevant:  the crime is simply  in having alcohol in the system. 

In this report, the Feds are now recognizing that the situation is even worse for drugged driving: there is no known way to determine for many (if not most) drugs how much is required to render a driver impaired.  As with alcohol per se laws, then, the Feds are recommending "solving" the problem by simply ignoring impairment and calling for laws making driving with the mere presence of the drug a crime.  And since they can’t determine what levels of hundreds of different drugs to outlaw, they will simply treat them the same and outlaw any amount of any of those drugs.

Easier to arrest, easier to prosecute, easier to convict…even if the driver was never a danger to anyone.

Thanks to attorney Troy McKinney  of Houston, Texas.

The post How Accurate is Detection and Evidence of Drugged Driving? appeared first on Law Offices of Taylor and Taylor - DUI Central.

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