Marijuana Legalization Creates Challenges for Officers Enforcing Impaired Driving Laws

marijuana legalization - LexipolThe battle to choose what substances are acceptable for recreational use was, is and will be a topic that polarizes society. Where has all the battling got us? Some argue that skyrocketing prison populations are the result of stringent initiatives. Others point out that a reduction in violent crimes is consistent with harsh penalties. Regardless of which side you take, there’s no arguing that drug laws have consequences far beyond whether people are jailed for possession.

Recently the question of recreational marijuana has become a mainstream topic. In several states, recreational use is now legal, and we can expect more states to follow suit. One major undecided factor of marijuana legalization involves how we develop and enforce laws governing stoned driving. In my last article, “We’ve Been Here Before: The Impact of Marijuana Legalization on DUI,” I shared three predictions about how the recent legalization trend would affect law enforcement officers tasked with keeping our streets safe (there is some evidence that as pot becomes more available, the percentage of intoxicated drivers with THC in their system increases). Those predictions were based in large part on our country’s history with alcohol, Prohibition, and DUI laws. In this article, we’ll delve into the issue of field sobriety testing and the importance of officer subjectivity while testifying in court.

Standardization and Field Sobriety Testing

The development and enforcement of DUI legislation were two very different things. As far back as the 1930s, scientific studies established that drunk driving was dangerous (Widmark in 1932, Heise in 1934 and Borkenstein in 1954). Eventually, this research, combined with the ability to measure blood alcohol content (BAC), led states to establish legal BAC limits first at .10%. This was later lowered to .08%, and the trend continues. For example, Utah House Bill 155 was signed into law in March 2017, lowering the BAC to .05%.

Knowing an act is dangerous and proving that an act is dangerous in court are two very different things. And early in society’s battle to fight DUI driving an important step was still missing: The ability of an officer in the field to judge whether a person’s behavior impaired their ability to operate a motor vehicle safely. Officers often conducted field sobriety tests (FSTs), but FSTs lacked reliability for evidentiary purposes because there was no set standard and evidence showing they directly correlated to a person’s BAC.

In 1981, on behalf of the National Highway Transportation Safety Administration (NHTSA), Tharp, Burns, and Moskowitz conducted research to standardize a battery of tests for field officers and streamline DUI arrest procedures. The resulting standardized field sobriety tests (SFSTs) were put into place by law enforcement agencies later that same year; they consist of three tests:1

  1. Horizontal Gaze Nystagmus
  2. Walk-and-Turn
  3. One-Leg Stand

Evidence Collection and the Beat Cop

Arguably, the current procedures and policies adopted by many law enforcement agencies for DUI detection are more than adequate to detect impaired driving for those consuming alcoholic beverages. However, field officers are faced with a gap in knowledge and unanswered questions on the best procedure to identify impairment for drivers under the influence of marijuana. At best, current field methods employ an ad hoc process that works like this:2

  • A deputy develops reasonable suspicion that a driver is intoxicated with alcohol, drugs or both based on articulable facts. Those facts are generally established in four ways: direct driving observation (e.g., pronounced weaving over a sustained period, speed fluctuations, slow speed), a citizen report, a vehicle accident or a vehicle stop for a vehicle code violation.
  • The deputy conducts a vehicle stop based on the reasonable suspicion for reasons cited above.
  • The deputy questions and observes the driver, and may administer SFSTs.
  • If the observation and/or the SFSTs develop into probable cause, the deputy arrests the driver.

But let’s add some complexity. What if the driver is intoxicated with something other than alcohol, or what if the driver is drunk and stoned? If the initial officer determines the impairment is not alcohol-related after conducting a series of SFSTs, a Drug Recognition Expert (DRE) is often called to the scene. The DRE officer completes another set of FSTs to detect impairment for substances like marijuana. The process is clumsy at best and inefficient, to say the least.

Frye, Daubert, and Admissibility

Case law on the scientific admissibility of DRE FSTs is contentious (see Drug Recognition Expert Testimony Cases). In part, the discussion revolves around whether the FSTs used by DREs are scientific evidence, expert testimony, or non-expert opinion testimony. Even the standard courts apply are different. For example, some states apply the Frye standard while other states employ the Daubert rationale.

As stated above subjectivity (officer opinion) is at play during the investigative process. An officer acting as a witness can testify about their opinion (subjectivity) but first must be deemed an “expert” by the court. After the court determines that an officer possesses the skills to be considered an expert the officer’s opinion can come into play. Two cases determine evidence admissibility standards: Frye v. United States (1923), and Daubert v. Merrell Dow Pharmaceuticals (1993).3,4

In Frye, the court determined that “Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while the courts will go a long way in admitting experimental testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs” (emphasis added).

Using the Frye standard, the question for the court became, “Is the procedure, technique or principle in question generally accepted by a meaningful proportion of the relevant scientific community?” The Frye standard requires “general acceptance” in the scientific community. But here’s the rub: Federal Evidence Rule 402, with certain exceptions, allows the admittance of all relevant evidence. The Frye standard by its very nature eliminates a great deal of relevant evidence that might not generally be accepted by the scientific community.

The contradiction on admissibility was dealt with in Daubert, where the Court ruled that the Frye standard conflicted with the Federal Evidence Rule. The Court reasoned that all relevant evidence is admissible.

In a nutshell, if the testimony occurs in a state employing the Daubert rationale, evidence is not automatically excluded because the evidence lacks general acceptance by the scientific community. Rather, a judge acting as a gatekeeper decides if the evidence has value. Value is based on “reliable principles and methods in the scientific community,” not necessarily “general acceptance.”

After an investigating officer is deemed an expert by the court, that officer may testify if the testimony is based upon sufficient data or facts, the testimony is the product of reliable principles and methods, and the expert has reliably applied the principles and methods to the case at hand.

Judicial gatekeeping helps ensure expert testimony is relevant and reliable, but it’s not without repercussions. According to Schweitzer and Saks (2009), when judges allow expert testimony to reach the jury, they implicitly lend credence to the testimony, increasing its persuasiveness and possibly tipping the scales toward the party offering the expert witness.5 In the case of DUI arrests, the investigating officer gains credibility if the testimony passes judicial review.

Where Are We Now?

Why do guidelines for admitting expert testimony matter in marijuana DUI cases? As I noted in my last article, we lack scientific evidence of the effects of THC on driving behavior. Further, while we can test for the amount of THC in the blood, the fact that marijuana remains in a person’s system days after consumption makes per se limits challenging to prove or disprove.

Some states have enacted laws redefining DUI as driving with a certain amount of THC in one’s blood. The Colorado legislature, for instance, set the limit at 5 ngm of delta-9-THC per milliliter, and other states have followed suit. But as Roth (2015) details, this approach is inherently flawed because DUI laws were based on controlled studies that established a correlation between BAC and single-car crashes.6 Such studies have yet to be completed for stoned driving. Until science can catch up, we will be forced to rely on expert testimony and officer opinion on an individual’s ability to safely operate a motor vehicle.

And at least right now, those experts differ. Just consider:

  • Roth claims the limited studies we do have “suggest, if anything, that drivers with only THC in their blood are not causing a disproportionate number of fatal crashes.”6
  • But a study by Ramaekers et al. (2004) showed that drivers with THC at higher doses are about three to seven times more likely to be responsible for a crash as compared to drivers who had not used drugs or alcohol.7
  • In one study, 30 frequent marijuana users abstained from use for a month. In some of them, THC was measurable in the blood for 30 days. The heavy users even tested above the 5-nanogram level—a level several states equate to a BAC of .08—for several days after they had stopped smoking.
  • But in another study, people who didn’t regularly consume marijuana showed no evidence of use on a blood test even after they immediately smoked a joint.

Not surprisingly, the lack of established consensus about THC and DUI is already being born out in the courts. A 2012 ruling in Maryland held that the DRE protocol failed to produce an accurate and reliable determination of whether a suspect is impaired by drugs and by what specific drug he is impaired. Furthermore, the court ruled the DRE training police officers receive does not enable DREs to accurately observe the signs and symptoms of drug impairment. Therefore, police officers are not able to reach accurate and reliable conclusions regarding what drug may be causing impairment.

A similar 2017 ruling in Massachusetts held an officer cannot opine on the question of a driver’s impairment from marijuana based on SFSTs. The tests are admissible “to establish a driver’s balance, coordination, and mental acuity,” the court said; the jury must reach its own conclusion about whether the driver was impaired.

The court’s comments, in this case, are extremely illustrative: “The scientific community has not reached a consensus as to whether a defendant’s performance on any combination of FSTs, or any individual FST, is correlated with marijuana use or impairment … Because the effects of marijuana may vary greatly from one individual to another, and those effects are as yet not commonly known, neither a police officer nor a lay witness who has not been qualified as an expert may offer an opinion as to whether a driver was under the influence of marijuana.”

The argument of substance use and tolerance to its effect is not new. In 1938 the National Safety Council and the American Medical Association teamed to develop per se limits for alcohol. The first upper limit chosen was 0.11%, but because there were “a few tolerant persons” among heavy drinkers at that level, 0.13% was proposed instead. Eventually, the committee decided to go even higher, to 0.15%, because “somewhere some person might be found who was still more tolerant than any seen by American experimenters.”8 Hopefully, society is not reliving the past, rather we are learning from it!

Where Are We Going?

Sheer economics—as well as the critical need to keep impaired drivers off the streets—will bring about much progress. In fact, we’re already seeing it. The San Diego Police Department recently debuted the use of a mouth-swab device to test for marijuana impairment, which is being used in more than a dozen states. The department says the machine tests for the active THC compound, not the inactive compounds that stay in the body’s system for weeks. It’s important to note, however, that the device doesn’t reveal the level of impairment; a blood test is necessary for that. And so we’re back to the inherent problems of blood testing for THC.

Other companies, such as Cannabix Technologies and Hound Labs, are working on developing breathalyzer-type devices that detect the concentration of THC in the breath and link it to the amount found in the blood.

Tara Lovestead, a chemical engineer at the National Institute of Standards and Technology in Boulder, Colo., is working on documenting the vapor pressure of THC. She believes standardizing that measurement could provide a more objective way to evaluate intoxicated drivers.

All these developments point at two critical research needs:

  • What exactly is the effect of THC on driving? Consider the advertisements for alcohol overindulgence that state, “Know When to Say When.” Implied impairment made clear what “when” is for alcohol and driving. However, what conclusions will society draw on marijuana? Where is the line and how do we draw it?
  • How do we accurately measure the amount of THC in the blood or breath?

While any new method of marijuana detection will undoubtedly be challenged in court for years, and standardized FSTs do not yet exist, law enforcement officers are not helpless in the meantime. As the Massachusetts ruling indicated, officers can still administer SFSTs, carefully document the results, and testify about them. And an officer’s objective observations about the basis for belief that a person is incapable of safely operating a car (e.g., slurred speech, odor of an alcoholic beverage/drug, staggered gait) still hold value, just as they have been used for years when officers confront drivers who refuse to submit to SFSTs. But the fact remains that this is a rapidly evolving area of the law. Stay tuned!

Jim Concannon

JAMES CONCANNON retired as a sergeant with the Sierra County (CA) Sheriff’s Office, where he served since 2001. From 2011 to 2015, he served as Undersheriff, then returned to the sergeant rank after an administration change. Concannon earned his bachelor’s degree in criminal justice from Sacramento State University in California and his master’s in criminology, law and society from the University of California-Irvine. He is also a professional services representative for Lexipol, helping law enforcement agencies implement policy and training.

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