Skip to main content

Intoxication & Drug Testing Validity Questioning

The Recreational use of and abuse of prescription and illicit drugs has grown in the last 15 years, and become a point of concern to both forensic and non-forensic physicians. Various regulatory agencies, insurance companies, and medicolegal processes such as workers compensation and personal injury defense have been utilizing the defense of intoxication (drugs of abuse and alcohol or a combination of either) in order to prove or disprove liability for injury. Commonly, three types of biological samples have been utilized. They are, blood, urine and hair. This determines if a person has used drugs (to strictly determine if the use occurred, as opposed to being under the influence), hair will retain drugs for several months, most commonly 3 months after the use. Urine will retain drugs or their metabolites for anywhere from several hours to several days, or in some rare occasion weeks, and blood will retain the drugs or their metabolites for several hours. Therefore, the use of blood is not relevant to determining whether the person has used drugs in the past (several days to weeks). To determine whether the person is impaired as a result of a drug of abuse, blood is the best biological tissue to be tested and the most accurate, because the levels in the blood or the presence of the drug in the bloodstream is a very important objective determinant in the process of diagnosing or ruling out the "impairment or under the influence of drugs" or the "intoxication defense". Positive hair samples for drugs of abuse do not equate with impairment, it only can determine that in the past a person has been using drugs (with a given limit). The presence of drugs of abuse in the urine can absolutely not be equated with impairment, but rather use in the last day or several days, and in some extreme cases a week. The presence of drugs or their metabolites in the blood testing does not prove impairment, because there is no scientific data to extrapolate the exact level of illegal drugs that will impair a specific user. That type of extrapolation has been made only for alcohol, which has a legal definition in driving statutes, Federal and State, as well as medical forensic extrapolation formulas. (For instance, the blood alcohol disappearance curve.) Commonly a toxicologist and forensic physician will be asked to determine whether urine positivity for illegal drugs indicates that that person was "under the influence" or "intoxicated" when an accident occurred on the job, or a car accident occurred on the road. The presence of drugs of abuse or even prescription medication in the urine, or their metabolites in the urine, cannot be equated with impairment. Unless clinical data from the site of injury or prior to the injury can indicate that the person was behaving as an impaired person, even then it will be very difficult to establish impairment. The presence of drugs or their metabolites in the blood may support impairment based on the blood levels and the clinical behavior. A marijuana positive in urine, which is not supported with evidence of behavioral impairment, cannot and does not speak to the question of drug "intoxication". This scientific fact is commonly, and for some reason, forgotten or is unknown to some forensic physicians who have the professional and ethical responsibility to evaluate whether the person was under the influence of illicit drugs. Behavioral science shows that stimulants are often difficult to detect, but it cannot be determined with certainty whether the misses are true errors. Since the half-life of cocaine is approximately 90 minutes, and the metabolite (breakdown products of cocaine) benzoylecgonine (BE) is known to have no psychoactive effect and can be detected for 24 or 48 hours (usually), urine positive for BE does not mean that the suspect was "under the influence" during the evaluation. THE CLEAR MESSAGE IS: 1. The presence of drugs of abuse in the urine cannot be used for the "intoxication defense". 2. The presence of drugs of abuse in the blood cannot automatically be extrapolated to the "intoxication" defense". 3. Each case requires careful analysis of the medical records and the clinical reliability of the blood levels. 4. The presence of drugs of abuse in hair has no meaning whatsoever and cannot support the "intoxication" defense. The only extrapolation to be made is that drugs were used sometime in the past. There are 161 prescription and over-the-counter medications, which have been studied and show that 65 of them produce false positive results in the commonly administered urine test for drugs. The widespread testing and reliance of telltale traces of drugs in the urine is simply a panic reaction invoked, because the normal techniques for controlling drug use have not worked very well. The next epidemic will be testing abuse." The most commonly used urine testing methodology is AMIV, has been shown that over 250 over-the-counter medications and prescription drugs can cause false positive testing using this methodology. The following have been reported as causing false positive tests are shown in the next table. Medications/Substances Causing False Positives/Cross-Reactions: Marijuana: Pain relievers such as Advil, Nuprin, Motrin and menstrual cramp medications like Midol and Trendar. All drugs containing Ibuprofen. Passive marijuana smoking. It has been described that passive marijuana inhalation at a rock concert can test positive in the urine despite the fact that the person has not been using marijuana. Amphetamines: Dristan Nasal Spray, Neosynephren, Vicks Nasal Spray, Sudafed, and others containing ephedrine or pnenypropanolamine. Opiates Vicks Formula 44M containing Dextromethorphan, and Primatene-M containing perylamine, as well as the pain reliever Demerol and prescription anti-depressant Elavil, and even Quinine Water. Methadone: NyQuil Nighttime Cold Medicine. Cocaine: Antibiotics such as Ampicillin and Amoxicillin. PCP: Diazepam, as well as some ingredients in cough medicines, Dextromethorphan. Opiates: Poppy seeds such as on a Burger King roll, bagel rolls (according to the Journal of Chemical Chemistry, Volume 33, #6, 1987), quantities of poppy seeds ingested in this study 25 and 40 grams, may be expected to be contained in 1 or 2 servings of poppy seed cake. Therefore, poppy seeds represent a potentially serious source of falsely positive results in testing opiate abuse. Not only is it difficult to distinguish heroine or morphine abuse from codeine, but also dietary poppy seeds can give strong positive results for urinary opiates for several days duration that is confirmed by GC/MS analysis. Ethnic Origin: The list of agents, which can cause false positivity in the urine, has also been described for endogenous excretion of enzymes in the urine. For instance, a percentage of persons of African origin, Orientals and Pacific Islanders may be testing positive for marijuana secondary to a mechanism which involves the pigment melanin which protects the skin from sun, which approximates the molecular structure of the THC metabolite which causes laboratory cross reaction with marijuana. What this means is that if you have used any of these over-the-counter medications, you may be accused or arrested, based on a false positive urine test. If your expert does not pick this up you may be in very serious trouble. There are several methods to detect drugs in the urine. The most frequent one is an enzyme immunoassay (EIA), or radioimmunoassay (RIA), and florescence polarization immunoassay (FPIA). There are additionally more sophisticated methodologies, which are performed on extract of urine, which are performed using thin layer chromatography (TLC), gas chromatography (GC) high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GS/MS). The only accepted procedures based on the definition of the National Institute of Drug Abuse (NIDA), and the Department of Defense (DOD), are immunoassays followed by gas chromatography/mass spectrometry confirmation. The confirmation utilizing gas chromatography/mass spectrometry is required since the methodology of immunoassay can give false positive results due to cross reactivity. This is due to the fact that this methodology cannot specifically identify the drug, but rather the antibodies recognize substances, which may have the same structure chemically, or immunologically or enzymologically, other than the drug of interest. Immunoassays for amphetamines will show reactivity with drugs structurally related to amphetamines, such over the counter sympatomedicoamines, phenylpropanolamine and ephedrine, over-the-counter legal medications used for nasal congestion, cold and appetite suppressant. Confirmation therefore is a must utilizing gas chromatography/mass spectrometry. The use of gas chromatography/mass spectrometry provides an extremely high index of reliability when properly preformed and applied. As far as gas chromatography/mass spectrometry, this is a superb methodology if done correctly. For instance, if the equipment has not been cleaned appropriately, the previous run from the previous testing will contaminate the next sample, and will give erroneous, inaccurate and incorrect results. Therefore, it is mandatory to look into the methodology that the person used for specific results on gas chromatography/mass spectrometry at a given indicated case. On many occasions interviewing/cross-examination of the lab technician will reveal that the sample was contaminated. What this means to you is that if your urine is tested utilizing the immunological method only, without confirmation with GS/MS, there is a high probability that the result may be a false positive and irrelevant to your situation. The forensic accuracy of gas chromatography/mass spectrometry is extremely and highly accurate if done correctly.

Rate this guide

Recommended articles about Criminal defense

Can’t find what you’re looking for?

Post a free question on our public forum.

Ask a Question

- or -

Search for lawyers by reviews and ratings.

Find a Lawyer