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A Drug Free Workplace

January 31, 2019 BY Earl King


Recreational marijuana is now legal in more states than ever before. Medical marijuana has been legalized in the state of Georgia for individuals with specific ailments. This may mean that a percentage of the workforce is impaired on the job. Many employers stopped pre-employment drug testing for marijuana because too many potential workers failed their drugs test, and because presence of marijuana in your system does not mean you are currently impaired. Right now, there is no reliable method for employers to determine whether an employee is impaired on the job. The question is, how close are we to uncovering a way to determine if an employee is impaired?

Georgia Law

Under Georgia law, no compensation shall be allowed for an injury or death due to the employee’s willful misconduct, including intentionally self-inflicted injury, or growing out of his or her attempt to injure another, or for the willful failure or refusal to use a safety appliance or perform a duty required by statute. O.C.G.A. § 34-9-17 (2010).

A positive drug/alcohol test does not automatically bar a workers’ compensation claim. It gives rise to a rebuttable presumption that the accident occurred because the employee was intoxicated. The burden then shifts to the employee to prove by clear, positive, and uncontradicted evidence that the accident did not occur because they were intoxicated. The rebuttable presumption also arises if the employee unjustly refuses to submit to a post-accident drug test. However, being intoxicated is not enough. There must be a link between the intoxication and the cause of the accident. Without this link, the intoxication cannot serve as a basis for denial of the claim.

There are important rules regarding the timeliness of how to conduct the drug screen and if those rules are not complied with, then the Employer/Insurer loses the presumption that the accident occurred because of the drugs or alcohol. The rules are outlined in O.C.G.A. § 34-9- 17(b)(1) and (2). If the test is positive, then the sample has to be taken within 3 hours of the accident for alcohol or 8 hours of the accident for drugs. If the samples are taken timely and the results are positive, then the rebuttable presumption is given to the Employer/Insurer that the injured worker was intoxicated and the intoxication led to the accident. If the test is not timely, then the Employer/Insurer has to prove to the court that the claimant was intoxicated and that the intoxication caused the accident. The rebuttable presumption eliminates that burden of proof requirement so the timeliness of the test is absolutely important. However, how reliable is the 8- hour time frame? What test is being used? Is the worker actually impaired?

Testing Temporal Impairment

In a study, the issue of temporal effects of marijuana were explored. Joseph E. Manno, Barbara R. Manno, Phillip M. Kemp, Dempsey D. Alford, Imad K. Abukhalaf, Mary E. McWilliams, Frances N. Hagaman, and Mary Jo Fitzgerald, Temporal Indication of Marijuana Use Can Be Estimated From Plasma and Urine Concentrations of Δ9 – Tetrahydrocannabinol, 11- Hydroxy- Δ9- Tetrahydrocannabinol, and 11-Nor- Δ9 –Tetrahydrocannabinol-9-Carboxylic Acid,

25  J.  of  Anal.  Tox.  538,  539  (2001).  The  psychoactive  element  of  marijuana,  Δ9   – Tetrahydrocannabinol (THC), is detected in the human body after it is hydroxylated by enzymes

to form 11-OH-THC. Oxidation of 11-OH-THC results in the most abundant THC metabolite found in blood and urine THC-COOH. THC has an incredibly short half-life, and as such an individual would have to be smoking marijuana at the time of an adverse event to be able to measure meaningful concentrations of THC. Clinical and forensic toxicologists are often called upon to interpret urine samples of THC-COOH because immediate testing of THC is not always available. No conclusive relationship between urine concentration and human psychomotor performance can be made from the levels of THC-COOH because it is not psychoactive. Furthermore, the long half-life of THC-COOH and normal renal physiology precludes establishing an accurate relationship between time, marijuana use, and urine concentrations.

Using drug metabolite to parent drug ratios for determining time has been suggested. A dihydroxymetabolite (8β, 11-dihydroxy-THC) that is eliminated within 24 hours in urine has also been suggested as a possible marker for recent marijuana use. A previous study suggested that free (8β, 11-dihydroxy-THC) was detected in urine following enzymatic hydrolysis within four hours of smoking two marijuana cigarettes prepared to deliver a total dose of 150 µg THC/ kg of body weight. The scientist who conducted the study suggested that a concentration of this THC metabolite greater than 15 to 20 ng/mL might indicate marijuana use within four to six hours of sample collection.

In a study with 8 participants, peak THC levels were present two hours after smoking and variations of THC levels amongst the participants was high. These variations can be accounted for due to the enzymes responsible for metabolizing cannabinoids. It is well documented that these enzymes are influenced by a number of factors including diet, age, gender, etc. The process used to measure the levels of THC was gas chromatography-mass spectrometry.

In the study participants were given two different marijuana cigarettes. One cigarette containing 1.77% THC and another containing 3.58% THC. The test of THC in the urine was conducted after enzymatic hydrolysis using bacterial β-glucuronidase from E.coli. Enzymatic hydrolysis was used to liberate unconjugated THC. The conductor of the study only used THC concentrations greater than or equal to 2 ng/mL. This allowed for the exclusion of very low residual concentrations of THC which may be present in frequent users even without the use of the drug in the very recent past (< 8hours).

The test results were that urinary THC concentrations fell below the limit of detection of the assay for the 1.77% and 3.58% THC doses at 5 hours and 7 hours respectively. Using the 2 ng/mL allowance the findings indicated that THC was only detectable in urine up to approximately 5 hours after smoking the high dose (3.58%) of marijuana.


This study suggests that concentrations of THC in urine greater than 2 ng/mL, following enzymatic hydrolysis, would be indicative of marijuana use within 5 hours of sample collection. This time frame is well within the time frame in which behavioral and performance effects are known to occur. Furthermore, urinary concentrations of THC greater than 1.5 ng/mL suggest marijuana use during the previous 8-hour time period. These data suggest that THC may be a biological marker for the identification of recent marijuana use.

The jury is still out on whether the 8-hour time frame used to determine whether a worker is impaired is effective. There are numerous factors that go into determining whether a person is actually impaired. Different levels of THC effect each person differently, and therefore, a test of the amount of THC in a person’s blood or urine may not be an accurate determination if they are “high,” or when they last ingested marijuana. There are many unanswered questions regarding testing for current impairment due to marijuana use. As more states move to legalize both recreational and medicinal marijuana, legal practitioners and employers will have to find a way to deal with this issue.

The Journal is a publication for the clients of Drew Eckl & Farnham, LLP. It is written in a general format and is not intended to be legal advice to any specific circumstance. Legal Opinions may vary when based upon subtle factual differences. All rights reserved. 

Editorial Board:

H. Michael Bagley