Correlating levels of blood and urine to impairment has also been extremely difficult in the past because of the absence of reliable studies linking specific levels of drugs in the blood or urine to impairment. Complicating this difficult task is the phenomenon of tolerance. While tolerance to alcohol has been studied at great length, tolerance to prescription medication is a much more individualized phenomenon. The absence of published medical studies on the subject has caused prosecutors to turn to the opinions of Drug Recognition Experts who are ready to render opinions about impairment.
Drug Recognition Experts are not doctors! It is impossible for them to distinguish between an anxiety attack and hyperactivity from a central nervous system stimulant. In addition, these Drug Recognition Experts are always attempting to correlate symptoms with “normal.” Since the officer has had no prior contact with the individual, it is impossible for him to determine what normal would be for any specific individual.
Prosecutors are also charging drivers with driving while under the influence of drugs even though their drug levels were within therapeutic ranges of their prescriptions. Since there are no per se levels in DUI-Drugs, impairment in fact must be shown. DUI-Drug cases can be defended successfully by attorneys who are knowledgeable in the deficiencies of the Drug Recognition Examination program, (2) are knowledgeable in the area of challenging drug testing, and (3) are committed to understanding the medical issues which inevitably are associated with prescription medication cases.
The National Highway Traffic Safety Administration has published Drug and Human Performance Fact Sheets . Please click on the links below for further information.
Because it is often impossible for the State to prove driving impairment based on drugs, it is important to determine the levels of the drugs in the bloodstream at or near the time of driving. This can be done by securing a blood split in order to have the blood retested by an independent laboratory. By doing so, you can more easily determine whether your client's levels of the drugs in his/her system are at, below, or above therapuetic ranges, and possibly whether your client was impaired at the time of driving. For instance, the chart below references some prescription drugs that are often used as a basis for alleging a violation of CVC ? 23152(a) and the levels of the drugs that are consider ed to be within therapuetic ranges. This information has been provided by National Medical Services (3701 Welsh Road, Post Office Box: 433A, Willow Grove, Pennsylvania 19090-0437) through retest results previously provided on other cases. National Medical Services is well-known laboratory for blood retesting.
View Prescription Drugs & Therapeutic Ranges
Depending on whether you know which drugs for which you would like to test, you can also run Drug Screens, such as an Opiate Screen, which will pick-up drugs like Hydrocodone; or a Benzodiazepine Screen, which will pick-up drugs like Xanax or Valium. A Drug Screen will assist you in determing whether any other drugs or their metabolites are present in your client's blood sample. This will assist you in determining the strength of your defense and it will also keep you in line with how the government laboratories conduct their testing because most government laboratories will run Drug Screens prior to running confirmation tests for specific types of drugs. For instance, it is not uncommon for government laboratories to run Drug Screens for the following characteristics of drugs: (1) Alkaline Drugs; (2) Weakly Acidic and Neutral Drugs; and (3) Benzodiazepines. Thus, because other drugs will sometimes be found in a blood sample that were not initially known to you, a Drug Screen will keep you a step ahead of the process and better prepare you for any surprises the government may find in your client's blood sample.
Please also keep in mind that experience has taught many of us who practice in DUI Drugs that the government laboratories rarely turn over the quantititative results and instead only provide you with proof that the prescription drugs were present in the system (qualitative results). The fact that it is not per se illegal to consume prescription drugs, the presence of them is of little value to the prosecution without proof that the individual's levels of the drugs rise to a level indicating impairment. Thus, it would be wise to conduct your own testing rather than relying on the government's test readings, especially since most government laboratories will not differentiate between "free" and "bound" levels and only report the "total" levels of the drugs. This is not a fair playing field; thus it is suggested that you have the blood retested in order to ascertain whether the prosecution can in fact prove up impairment.
View Identification & Investigation Chart
Marijuana And Actual Driving Performance Executive Summary
National Highway Traffic Safety Administration
By Robbe HWJ, O'Hanlon JF
November 1993
The relation between driving impairment following marijuana smoking and plasma concentrations of THC and THC-COOH is discussed. It appears not possible to conclude anything about a driver's impairment on the basis of his / her plasma concentrations of THC and THC-COOH determined in a single sample.
Abstract: This report concerns the effects of marijuana smoking on actual driving performance. It presents the results of one pilot and three actual driving studies. The pilot study's major purpose was to establish the THC dose current marijuana users smoke to achieve their desired "high". From these results it was decided that the maximum THC dose for subsequent driving studies would be 300 mcg / kg (0.3 mg / kg). The first driving study was conducted on a closed section of a primary highway. After smoking marijuana delivering THC doses of 0, 100, 200, and 300 mcg / kg, subjects drove a car while maintaining a constant speed and lateral position. This study was replicated with a new group of subjects, but now in the presence of other traffic. In addition, a car following test was executed. The third driving study compared the effects of a modest dose of THC (100 mcg / kg) and alcohol )BAC of 0.04 g %) on city driving performance. This program of research has shown that marijuana, when taken alone, produces a moderate degree of driving impairment which is related to the consumed THC dose. The impairment manifests itself mainly in the ability to maintain a steady lateral position on the road, but its magnitude is not exceptional in comparison with changes produced by many medicinal drugs and alcohol. Drivers under the influence of marijuana retain insight in their performance and will compensate where they can, for example, by slowing down or increasing effort. As a consequence, THC's adverse effects on driving performance appear relatively small.
Although cannabis intoxication has been shown to mildly impair psychomotor skills, this impairment does not appear to be severe or long lasting. In driving simulator tests, this impairment is typically manifested by subjects decreasing their driving speed and requiring greater time to respond to emergency situations. Nevertheless, this impairment does not appear to play a significant role in on-road traffic accidents. A 2002 review of seven separate studies involving 7,934 drivers reported, "Crash culpability studies have failed to demonstrate that drivers with cannabinoids in the blood are significantly more likely than drug-free drivers to be culpable in road crashes." This result is likely because subject under the influence of marijuana are aware of their impairment and compensate for it accordingly, such as by slowing down and by focusing their attention when they know a response will be required. This reaction is just the opposite of that exhibited by drivers under the influence of alcohol, who tend to drive in a more risky manner proportional to their intoxication.
Today, a large body of research exists exploring the impact of marijuana on psychomotor skills and actual driving performance. This research consists of driving simulator studies, on-road performance studies, crash culpability studies, and summary reviews of the existing evidence. To date, the result of this research is fairly consistent: Marijuana has a measurable yet relatively mild effect on psychomotor skills, yet it does not appear to play a significant role in vehicle crashes, particularly when compared to alcohol.
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