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Highway Safety Initiatives

Marijuana and Driving

By Richard J. Ashton, Chief of Police (Retired), Frederick, Maryland; and Grant/Technical Management Manager, IACP

The highway-safety question du jour is not whether police officers support or oppose the legalization of either marijuana or medical marijuana. After all, the legalization of medical marijuana with varying provisions has occurred in 20 states and the District of Columbia since 1996 and is currently pending in 4 more states, even though marijuana and tetrahydrocannabinol (THC) remain classified as Schedule I controlled substances under U.S. law.1

Recreational marijuana sales became legal in both Colorado and Washington in 2012.2 Those Coloradans 21 years old or older may privately possess—or transfer without remuneration—one ounce or less of marijuana or privately cultivate up to six marijuana plants, with no more than three being mature.3 Washington permits “an adult to possess up to one ounce of cannabis (and/or up to 16 ounces of marijuana-infused product in solid form, and 72 ounces of marijuana-infused product in liquid form) for their own personal use in private.”4

Instead, today’s issue is how police officers are dealing—or will deal—with the reality of those who drive vehicles after using marijuana. It clearly poses a grave challenge to traffic law enforcement efforts that strive to ensure safe highways in spite of those legally entitled to use marijuana under state laws. A recent study in Colorado underscores the seriousness of the issue:

  • Overall traffic fatalities in Colorado decreased 16 percent between 2006 and 2011. However, during these same six years, traffic fatalities involving those drivers testing positive for just marijuana increased 114 percent.
  • Colorado’s traffic fatalities involving drivers testing positive for marijuana in 2006 represented only 5 percent of total traffic fatalities. However, by 2011, that percentage had more than doubled to 13 percent.
  • Drivers testing positive for marijuana in 2006 were involved in 28 percent of fatal vehicle crashes involving drugs. However, by 2011, that percentage had increased to 56 percent.5

Significantly, less than half of Colorado’s fatalities were tested between 2006 and 2011 for the presence of drugs.6 Unfortunately, the failure to test meaningful numbers of fatally injured drivers for drugs is not limited only to Colorado. Drug testing of fatally injured drivers in the United States ranged from 56 percent in 2005 to 63 percent in 2009.7

Police chief executives need to familiarize themselves with the issues that involve marijuana and driving, so they can create and launch effective strategies that ensure the safety of highway users if marijuana is legalized in their jurisdictions. Several of these issues are set forth below for consideration:

Promote per se laws. Encourage the enactment of per se drugged driving statutes rather than those based on the affected by standard.8 Per se drugged driving statutes, which currently have been adopted in 18 states, simply make the presence of any illegal drug—or of any illegal drug above an established cutoff level—in a driver’s body evidence of impaired driving.9 This zero tolerance standard negates the need to prove a driver’s impairment by illegal drugs, which is fortuitous since “there is no scientific basis for specifying a bodily fluid concentration that is indicative of impairment.”10 On the other hand, affected by driving under the influence of drugs (DUID) statutes require proof that a driver took a drug, including a lawfully prescribed one, and that it impaired the driver’s ability to operate a vehicle.11 The Federal Motor Carrier Safety Administration provided a successful model in its promulgation for commercial vehicle drivers of a per se standard for illegal drugs, as well as an affected by standard for prescription drugs, more than two decades ago; these regulations illustrate the highway safety benefits of such a dual approach.12

A related issue involves the cutoff level: whether to establish one and the point at which to set it. Only 3 of the 15 states enacting per se drugged driving statutes adopted cutoff levels.13 For marijuana, both Nevada and Ohio set 10 nanograms per milliliter (ng/mL) for urine and 2 ng/mL for blood; for marijuana metabolites, 15 ng/mL for urine and 5 ng/mL for blood.14 For THC, Pennsylvania established 5 ng/mL for blood; Washington enacted a 5 ng/mL for blood per se statute; and Colorado passed a 5 ng/mL for blood affected by law.15 However, research suggests that setting a cutoff level at less than 5 ng/mL for blood would fail to identify many drivers who smoked cannabis because THC is rapidly cleared from the blood.16

More drug recognition experts (DREs). States’ legalization of marijuana presents an opportunity to expand substantially the number of trained and credentialed drug recognition experts (DREs) under the Drug Evaluation and Classification Program (DECP) that the IACP has operated since 1989.17 Prospective DREs receive more than 100 hours’ intensive training—based upon the standard field sobriety tests (SFSTs)—in how to conduct systematic and standardized 12-step evaluations consisting of physical, mental, and medical components.18 One of the benefits that DREs offer is the ability to indicate which of the seven classes of drugs may be affecting an individual, so that laboratory testing can be focused and its costs reduced.19 The DECP has been evaluated and deemed effective in identifying drug-impaired drivers.20 Currently, all 50 states and the District of Columbia participate in the DECP, which has credentialed 7,247 DREs, including 1,419 instructors.21

Train officers in Advanced Roadside Impaired Driving Enforcement. In this era of ever-shrinking budgets, the 16-hour Advanced Roadside Impaired Driving Enforcement (ARIDE) program is ideal for law enforcement agencies that already have trained their officers in the SFST, but cannot afford to invest the considerable time required to train additional DREs. ARIDE is a force multiplier that relatively quickly can enhance DUID enforcement efforts, inasmuch as it was created to compensate for the gap in knowledge between SFST and DRE training. While successfully completing the ARIDE program does not qualify officers as DREs, officers’ proficiency in administering the SFST will be enhanced, and their ability to discern when a DRE’s expertise is required will be improved.22 The ARIDE program presently is taught in at least 34 states, and an online version of the ARIDE program has just become available to allow the training of exponentially more officers.23

Support telephonic search warrants.24 A non- DRE officer who lawfully detains a driver unable to complete successfully the SFST and registering a blood alcohol concentration (BAC) of .02 grams per deciliter (g/dL) on a preliminary breath test and who observes no obvious evidence of drug use is able to obtain additional evidence to support the probable cause initially developed for a DUID charge, when a statute providing for a telephonic search warrant trumps the driver’s refusal to submit a blood sample. Seven (Arizona, Illinois, Indiana, Ohio, Pennsylvania, Rhode Island, and Utah) of fifteen states in which it is illegal per se to operate a motor vehicle with certain drugs, including marijuana, in one’s system authorize telephonic search warrants to secure an evidentiary blood sample.25

Train police officers as phlebotomists.26 If law enforcement agencies expect their officers to effect a greater number of DUID arrests, officers must possess the tools essential to secure evidence quickly. Officers generally are limited to obtaining blood, urine, or oral fluid samples. In fact, all 15 states that enacted per se drugged driving statutes permit the collection of blood samples; 6 (Arizona, Delaware, Georgia, Illinois, Iowa, and Minnesota) of those states allow the collection of urine samples; and 16 states authorize the collection of other bodily substances.27

The issue of training police officers as phlebotomists is intrinsically related to that of telephonic search warrants because “THC is rapidly cleared from the blood after smoking marijuana,” and “nearly all marijuana users test below 5 ng/mL of active THC in blood only a few hours after their last use.”28 For example, if a blood sample is taken from an arrestee 30 to 90 minutes after apprehension, the THC concentration, like the BAC, will be lower than it was at the time of arrest, so time is of the essence.29 Officers trained in phlebotomy can expedite the process of collecting an evidentiary blood sample to ensure it complies with any period of time prescribed by law. Six (Arizona, Indiana, Ohio, Pennsylvania, Rhode Island, and Utah) of fifteen states in which it is illegal per se to operate a motor vehicle with certain drugs, including marijuana, in one’s system, permit blood to be withdrawn by officers trained in phlebotomy.30 Such a procedure improves the quality of the evidentiary sample, which is fair both to arresting officers and to defendants and encourages officers to pursue a DUID charge, an alcohol-impaired driving violation, or both, depending upon how a state’s statute was enacted.

Decide how to handle seized plants. Police chief executives must be wary of statutes that require the return of evidence in the event of acquittals. Such laws, in effect, require law enforcement agencies to maintain medical marijuana plants, including those seized during traffic stops, throughout the entire trial process to avoid payment of damages in the event of “not guilty” verdicts.31 Consequently, police chief executives must coordinate with legislators, prosecutors, and crime laboratories to determine how evidence of seized marijuana plants needs to be processed by law enforcement agencies to ensure that statutes are not violated, evidence is admissible at trial, and liability does not attach.32

Dog sniffs for marijuana. For the past 30 years, police officers successfully have conducted U.S. Supreme Court–sanctioned dog sniffs for various illegal drugs during lawful traffic stops.33 However, the legalization of marijuana creates a dilemma: What if a dog sniff in Colorado or Washington results only in the seizure of less than one ounce of marijuana? Is there liability in this situation for the canine officer and/or the law enforcement agency? What is the status of other evidence, such as counterfeit money, discovered during the subsequent search of the vehicle? Police chief executives must decide how to deal with such detections. Washington State Patrol Chief John R. Batiste reported that arrests based upon the discovery of marijuana by current drug detection canines are justified only when other factors exist, that is, the smell of marijuana alone, like the smell of alcohol alone, will not justify an arrest; and new canines no longer will be trained in the detection of marijuana.34

Second-hand smoke. Police officers could encounter drivers unintentionally operating under the influence of marijuana. As bizarre as this seems, the driver of a limousine or a motor home in Colorado could be affected by second-hand marijuana smoke lawfully created by passengers seated behind the driver.35

Promote continued research into roadside drug tests. Currently, “it is not possible to identify a valid impairment standard for marijuana or any other drug equivalent to the 0.08 g/dL limit for alcohol.”36 Therefore, police chief executives must advocate for continued “research to improve the standards and reliability for drug testing, including the development of a reliable and widely-available roadside test for the detection of the presence of drugs in drivers’ systems” such as oral fluid (saliva).37

The foregoing discussion certainly is not intended to be all inclusive; its purpose is to alert police chief executives to issues that could arise if the legalization of marijuana or medical marijuana is contemplated in their jurisdictions, so they can proactively advocate sound approaches to balance the legislative proposals with highway safety. Remember, the overarching issue is marijuana and driving. ♦

Notes:, “20 Legal Medical Marijuana States and DC,” September 16, 2013, (accessed October 16, 2013);, “Four States with Pending Legislation to Legalize Medical Marijuana,” Medical Marijuana, August 21, 2013, (accessed October 16, 2013); 21 U.S.C. § 812 I (c) (10) & (17), (accessed October 28, 2013); a controlled substance found in schedule I is a drug or other substance that has a high potential for abuse, no currently accepted medical use in treatment in the United States, and for which there is a lack of accepted safety for its use under medical supervision. 21 U.S.C. § 812 (b) (1) (A–C), (accessed October
28, 2013).
2Niraj Chokshi, “After Legalizing Marijuana, Washington and Colorado Are Starting to Regulate It,” GovBeat, The Washington Post, October 9, 2013, (accessed October 18, 2013).
3NORML, “Colorado Laws & Penalties,” (accessed October 18, 2013).
4NORML, “Washington Legalization,” (accessed October 18, 2013).
5Rocky Mountain High Intensity Drug Trafficking Area, The Legalization of Marijuana in Colorado: The Impact (August 2013), 5, (accessed October 18, 2013).
6Ibid., 7.
7“Drug Involvement of Fatally Injured Drivers,” NHTSA, Traffic Safety Facts, November 2010, DOT HS 811 415, 1, (accessed October 29, 2013).
8Institute for Behavior and Health, Inc., Drugged Driving Committee, Drugged Driving Research: A White Paper, by Robert L. DuPont et al., for the National Institute on Drug Abuse (March 31, 2011), 7, 25, (accessed October 29, 2013).
9Governors Highway Safety Association, “Drug Impaired Driving Laws,” October 2013, (accessed October 27, 2013).
10“Drug Per Se Laws: A Review of Their Use in the States,” NHTSA, Traffic Tech, September 2010, no. 393, 1, (accessed October 26, 2013).
11DuPont, Drugged Driving Research, 23, 25–26, 43.
12Ibid., 39; also see 49 CFR § 392.4. Drugs and Other Substances, and 49 CFR Part 382, Controlled Substances and Alcohol Use and Testing, (both accessed November 13, 2013).
13John Lacey, Katharine Brainard, and Samantha Snitow, Drug Per Se Laws: A Review of Their Use in States, July 2010, DOT HS 811 317, 5, (accessed October 26, 2013).
14Ibid., 82, 88.
15Ibid., 185; Washington State Legislature, RCW 46.61.502. Driving under the influence. (accessed October 26, 2013); and Robert L. DuPont, “Marijuana Use Is a Serious Highway Safety Threat: 5 ng/ml Marijuana Impairment Limits Give Drivers a Free Pass to Drive Stoned,” Commentary, June 10, 2013, 2, (accessed October 27, 2013).
16DuPont, Drugged Driving Research, 13.
17The International Drug Evaluation and Classification Program (DECP), “About DECP,” (accessed October 26, 2013).
18DECP, “DRE Training & Certification,” (accessed October 26, 2013).
19DuPont, Drugged Driving Research, 18.
20Ibid., 31–32.
21DEC Program Manager Carolyn Cockroft, personal interview with author, October 28, 2013.
22DECP, “DRE Training & Certification.”
23Colorado Amendment 64 Implementation Task Force, Task Force Report on the Implementation of Amendment 64, March 13, 2013, 84, (accessed October 29, 2013); U.S. Office of National Drug Control Policy (ONDCP), National Drug Control Strategy (Washington, D.C.: 2013), 67, (accessed November 13, 2013).
24For additional information, see J.H. Hedlund and D.J. Beirness, Use of Warrants for Breath Test Refusal: Case Studies, October 2007, DOT HS 810 852, (accessed January 19, 2012).
25Lacey, Brainard, and Snitow, Drug Per Se Laws, 14, 71, 75, 91, 96, 100, 105.
26For additional information, see Robert L. Ticer, “The Role of the Law Enforcement Phlebotomist,” The Police Chief 72 (September 2005): 122–125, (accessed January 13, 2012).
27Lacey, Brainard, and Snitow, Drug Per Se Laws, 14, 48, 62, 67, 71, 79; DuPont, Drugged Driving Research, 39.
28DuPont, “Marijuana Use Is a Serious Highway Safety Threat,” 1.
29DuPont, Drugged Driving Research, 13.
30Lacey, Brainard, and Snitow, Drug Per Se Laws, 14, 75, 91, 96, 100, 105–106.
31Lance Benzel, “Fights over Medical Marijuana Case Evidence Could Be Costly,” The Gazette, January 4, 2013, (accessed October 27, 2013).
32Colorado Bureau of Investigation Forensic Laboratory, “Criminalistic and Trace Evidence,” A. Drugs and Controlled Substances, 1. Plant Matter, Physical Evidence Handbook, version 5.1 (August 2007), (accessed October 27, 2013).
33United States v. Place, 462 U.S. 696, 707 (1983); Indianapolis v. Edmond, 531 U.S. 32, 40 (2000); and Illinois v. Caballes, 543 U.S. 405, 410 (2005).
34Chief Batiste made these points during the IACP State and Provincial Police Directorate’s Annual Meeting, October 19, 2013, Philadelphia, Pennsylvania.
35Colorado Revised Statutes, C.R.S. 42-4-1305.5.
36DuPont, “Marijuana Use Is a Serious Highway Safety Threat,” 1.
37ONDCP, National Drug Control Strategy, 67, 69.

Please cite as:

Richard J. Ashton, “Marijuana and Driving,” Highway Safety Initiatives, The Police Chief 80 (December 2013): 92–94.



From The Police Chief, vol. LXXX, no. 12, December 2013. Copyright held by the International Association of Chiefs of Police, 515 North Washington Street, Alexandria, VA 22314 USA.

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