Per se driving limits for the presence of THC are arbitrary and may improperly classify motorists who are not behaviorally impaired, according to the findings of a study published today by the American Automobile Association (AAA) Foundation for Traffic Safety.
Per se driving limits criminalize the act of operating a motor vehicle if the driver possesses detectable amounts of specific drugs or drug metabolites above a set threshold. Under these laws, drivers are guilty per se of violating the traffic safety laws even absent evidence of demonstrable behavioral impairment.
Five states – Montana, Nevada, Ohio, Pennsylvania, and Washington – presently impose per se limits for the detection of specific amounts of THC in blood while eleven states (Arizona, Delaware, Georgia, Illinois, Indiana, Iowa, Michigan, Oklahoma, Rhode Island, Utah, and Wisconsin) impose zero tolerant per se standards. In Colorado, the presence of THC in blood above 5ng/ml “gives rise to permissible inference that the defendant was under the influence.” Legislation similar to Colorado’s law is presently pending in California.
However, the AAA report concludes, “[A] quantitative threshold for per se laws for THC following cannabis use cannot be scientifically reported.” This is because the body metabolizes THC in a manner that is significantly distinct from alcohol. In particular, acute effects of cannabinoids lag well behind the presence of maximum THC/blood levels. Additionally, residual levels of THC may be present in blood for extended periods of time, long after any psychomotor-related effects have ceased.
The Automobile Association’s finding is similar to that of the US National Highway Traffic Safety Administration, which acknowledges: “It is difficult to establish a relationship between a person’s THC blood or plasma concentration and performance impairing effects. … It is inadvisable to try and predict effects based on blood THC concentrations alone.”
NORML has long articulated a similar opposition to the imposition of per se driving thresholds for THC and/or its metabolites, stating, “[R]ecently adopted statewide per se limits and zero tolerant per se thresholds in the United States criminally prohibiting the operation of a motor vehicle by persons with the trace presence of cannabinoids or cannabinoid metabolites in their blood or urine are not based upon scientific evidence or consensus. … [T]he enforcement of these strict liability standards risks inappropriately convicting unimpaired subjects of traffic safety violations, including those persons who are consuming cannabis legally in accordance with other state statutes.”
Cannabis-influenced driving performance is significantly different from alcohol-induced driving behavior, according to driving simulator data published in the Journal of Applied Toxicology.
Investigators with the National Institute on Drug Abuse and the University of Iowa evaluated simulated driving performance in subjects following their consumption of vaporized cannabis, alcohol, or placebo.
Researchers reported that cannabis administration was associated compensatory driving behavior, such as decreased mean speed and increased mean following distance, whereas alcohol administration was associated with faster driving. Their findings are similar to those of other driving studies, like those here and here.
Investigators also reported that cannabis dosing in combination with low quantities of alcohol “mitigated drivers’ tendency to drive faster with alcohol” – a finding that contrasts with prior data acknowledging that the two substances combined typically possess an additive adverse effect on psychomotor performance.
“THC concentration-dependent associations with decreased speed, increased time below the speed limit and increased following distance suggest possible awareness by drivers of potential impairment and attempts to compensate,” authors concluded. “The compensatory behavior exhibited by cannabis-influenced drivers distinctly contrasts with an alcohol-induced higher risk behavior, evidenced by greater percent speed.”
According to the findings of a recently published literature review of crash culpability studies, “[A]cute cannabis intoxication is related to a statistically significant risk increase of low to moderate magnitude [odds ratio between 1.2 and 1.4].” By contrast, a 2015 case-control study by the US National Highway Traffic Safety Administration reported that driving with legal amounts of booze in one’s system is associated with a nearly four-fold increased crash risk (odds ratio = 3.93).
An abstract of the study, “Cannabis effects on driving longitudinal control with and without alcohol,” appears online here.
NORML reviews the top news stories of 2015.
#1 Congress Reauthorizes Medical Marijuana Protections
Members of Congress approved language in the fiscal year 2016 omnibus spending bill that continues to limit the federal government from taking punitive action against state-licensed individuals or operations that are acting are in full compliance with the medical marijuana laws of their states. The provisions reauthorize Section 538 of the Continuing Appropriations Act of 2015, which states, "None of the funds made available in this act to the Department of Justice may be used … to prevent … states … from implementing their own state laws that authorize the use, distribution, possession, or cultivation of medical marijuana."
#2 Federal Judge Upholds Marijuana’s Schedule I Status
A federal judge in April rejected a motion challenging the constitutionality of cannabis’ classification as a Schedule I prohibited substance. "At some point in time, a court may decide this status to be unconstitutional," Judge Kimberly Mueller said from the bench. "But this is not the court and not the time." Judge Meuller had presided over five days of hearings in October 2014 in a challenge brought by members of the NORML Legal Committee.
#3 Medical Cannabis Access Associated With Less Opioid Abuse
States that permit qualified patients to access medical marijuana via dispensaries possess lower rates of opioid addiction and overdose deaths, according to a study published in July by the National Bureau of Economic Research, a non-partisan think-tank. The findings mirror those published in 2014 in The Journal of the American Medical Association concluding, "States with medical cannabis laws had a 24.8 percent lower mean annual opioid overdose mortality rate compared with states without medical cannabis laws."
#4 DC Depenalizes Marijuana; Arrests Plummet
Despite threats from members of Congress, District officials implemented voter-approved legislation earlier this year eliminating penalties associated with the possession and cultivation of personal use quantities of marijuana by adults. Following the law’s implementation, marijuana-related arrests in the nation’s capital fell 99 percent.
#5 Marijuana Law Changes Don’t Change Youth Use, Attitudes
Rates of youth marijuana use are unaffected by changing laws, according to data published in July in The American Journal of drug and Alcohol Abuse. Investigators evaluated trends in young people’s attitudes toward cannabis and their use of the substance during the years 2002 to 2013 – a time period where 14 states enacted laws legalizing the medical use of the plant, and two states approved its recreational use by adults. "Our results may suggest that recent changes in public policy, including the decriminalization, medicalization, and legalization of marijuana in cities and states across the country, have not resulted in more use or greater approval of marijuana use among younger adolescents," researchers reported.
#6 Gallup Poll: More Americans Than Ever Say Marijuana Should Be Legal
Fifty-eight percent of Americans believe that "the use of marijuana should be made legal," according to nationwide survey data released in October by Gallup pollsters. The percentage ties the highest level of support ever reported by Gallup, which has been measuring Americans’ attitudes toward cannabis since the late 1960s. The percentage is more than twice the level of support reported in the mid-1990s.
#7 Study: Marijuana Use Not Associated With Changes In Brain Morphology
Marijuana use is not associated with structural changes in the brain, according to imaging data published in January in The Journal of Neuroscience. Investigators assessed brain morphology in both daily adult and adolescent cannabis users compared to non-users. They found "no statistically significant differences … between daily users and nonusers on volume or shape in the regions of interest" after researchers controlled for participants’ use of alcohol. "[T]he results indicate that, when carefully controlling for alcohol use, gender, age, and other variables, there is no association between marijuana use and standard volumetric or shape measurements of subcortical structures," researchers reported.
#8 Marijuana Consumers Less Likely To Be Obese, Suffer Diabetes Risk
Those who consume cannabis are 50 percent less likely to suffer from metabolic syndrome as compared to those who do not, according to findings published in November in The American Journal of Medicine. Metabolic syndrome is a group of risk factors, including high blood pressure, high blood sugar, unhealthy cholesterol levels, and abdominal fat, which are linked to increased risk of heart disease and adult onset diabetes, among other serious health consequences. The findings are similar to those of previous studies reporting that those who use cannabis are less likely to be obese or suffer from diabetes.
#9 NHTSA: THC-Positive Drivers Don’t Possesses Elevated Crash Risk
Drivers who test positive for the presence of THC in their blood are no more likely to be involved in motor vehicle crashes than are drug-free drivers, according to a case-control study released in February by the United States National Highway Transportation and Safety Administration. Authors reported that drivers who tested positive for the presence of THC possessed an unadjusted, elevated risk of accident of 25 percent (Odds Ratio=1.25) compared to controls (drivers who tested negative for any drug or alcohol). However, this elevated risk became insignificant (OR=1.05) after investigators adjusted for demographic variables, such as the drivers’ age and gender. The study is the largest of its kind ever conducted in the United States.
#10 Legal Marijuana States Collect Over $200 Million In New Tax Revenue
Taxes on the legal production and sale of cannabis in the states of Colorado and Washington have yielded over $200 million in new revenue since going into effect in 2014, according to calculations reported by The Huffington Post in September. Colorado collected more than $117 million dollars from marijuana sales while Washington collected over $83 million. Cannabis sales commenced in Oregon in on October 1, 2015 and have yet to begin in Alaska.
Republican Gov. Bruce Rauner on Friday issued an amendatory veto to House Bill 218, which seeks to decriminalize minor marijuana possession offenses.
As initially approved by the legislature in May, HB 218 reduced personal use possession penalties (up to 15 grams) from a Class A criminal misdemeanor, punishable by up to 6 months in jail, a $1,500 fine, and a criminal record, to a petty offense, punishable by a fine only (up to $125.00) – no arrest, and no criminal record. Governor Rauner’s amendatory veto seeks to decrease the proposed possession limits from 15 grams to 10 grams, whole also seeking to raise fines to $200.00.
Governor Rauner also seeks to lower the state’s proposed per se THC/blood limit from 15ng/ml to 5ng/ml. Under present Illinois law, drivers with any detectable amount of THC in their blood are in violation of the state’s traffic safety laws.
If a majority of lawmakers fail to approve of the Governor’s amendments, the measure will be dead for this year’s legislative session.
To date, 20 states and Washington, DC have passed legislation eliminating the threat of incarceration for marijuana possession offenses via either legalization or decriminalization.
Drivers who test positive for the presence of THC in blood are no more likely to be involved in motor vehicle crashes than are drug-free drivers, according to a federally sponsored case-control study involving some 9,000 participants. The study, published Friday by the United States National Highway Traffic Administration (NHTSA), is the first large-scale case-control study ever conducted in the United States to assess the crash risk associated with both drugs and alcohol use by drivers.
Authors reported that drivers who tested positive for any amount of THC possessed an unadjusted, elevated risk of accident of 25 percent (Odds Ratio=1.25) compared to controls (drivers who tested negative for any drug or alcohol). However, this elevated risk became insignificant (OR=1.05) after investigators adjusted for demographic variables, such as the drivers’ age and gender. After researchers controlled for both demographic variables and the presence of alcohol, THC-positive drivers’ elevated risk of accident was zero (OR=1).
By contrast, researchers reported that drivers who tested positive for low levels of alcohol possessed a statistically significant risk of accident, even after controlling for demographic variables (e.g., Drivers with a BAC of 0.03 possessed a 20 percent greater risk of motor vehicle accident [OR=1.20] compared to controls). Drivers with BAC levels of 0.05 possessed a greater than two-fold risk of accident (OR=2.07) while motorists with BAC levels of 0.08 possessed a nearly four-fold risk of accident (OR=3.93).
Researchers did not analyze drivers’ THC levels to similarly estimate whether higher or lower THC levels may impact crash risk in a dose-dependent manner, as has been previously reported in some separate analyses of fatal crash data.
Authors concluded, “This finding indicates that these other variables (age, gender, ethnicity, and alcohol use) were highly correlated with drug use and account for much of the increased (crash) risk associated with the use of illegal drugs and THC.”
The study’s finding contradict allegations by NIDA and others that “marijuana use more than doubles a driver’s risk of being in an accident,” but are largely consistent with those of a 2013 literature review published in the journal Accident Analysis and Prevention which reported that cannabis-positive drivers did not possess a statistically significant risk of a either fatal accident or a motor vehicle accident causing injury.
See NORML’s white paper on cannabis and psychomotor performance here.