Standardizing Marijuana Metrics: Challenging Law Enforcement’s System of Perfunctory Oversight

Current marijuana impairment metrics are not only questionable because they reveal shortcomings within modern jurisprudence, but also because they perpetuate ineffective penal codes and legal sanctions. As of now, no verifiable measure exists for marijuana intoxication and there is no widely accepted test for tetrahydrocannabinol (THC), its active ingredient. As such, federal, state, and district courts face a consensus problem: the validity of verdicts becomes confounded due to ambiguous policies classifying cannabis levels. Complicating the issue, current methodology prevents courts from employing certain admissible evidence mechanisms efficiently.

Due to the increasing popularity of cannabis, the legal system must undergo significant reform to mitigate malpractice and ensure proper corroboration. It can be argued that contemporary policies fail to set a firm legislative barrier against those driving while impaired. Conversely, not having clear, denotative standards skews the legal process, defrauding an individual’s civil rights through potentially false accusations and convictions.

Marijuana legislation varies from state to state; therefore, it is paramount that accurate, concordant measurement metrics and practices are enforced throughout the country as to not violate constitutional law by infringing upon unreasonable search and seizure protections.[1] In comparison, alcohol intoxication is tested using breathalyzers, which attenuates ambiguity and lessens the civic burden of ensuring proof beyond a reasonable doubt. Driving with a BAC (blood alcohol concentration) of 0.08% is illegal in all fifty states.[2] Due to their similar effects, it follows that alcohol and marijuana impairment would be handled in a parallel manner.

The physical implications of marijuana are contentious. Even so, cannabis is the drug found most often in the blood of drivers involved in vehicle crashes. The substance is correlated with impaired motor skills, reaction time, and judgment; studies have also linked blood THC concentration to incapacitated driving.[3] Seeking to reveal flaws within the cannabis metric system, a 2016 study by the AAA Foundation for Traffic Safety showed that, at every THC concentration threshold examined, the Standardized Field Sobriety Test would have misclassified a substantial number of drivers as unimpaired. These inaccurate measures accentuate the burden of preserving morality within our nation’s retributive justice system through interfering with arraignment, indictment, and sentencing guidelines.[4]

Entrenched in these debates are court cases like Commonwealth vs. Thomas J. Gerhardt, which reach toward the fundamental goals of reforming and understanding the limitations of currently admissible evidence mechanisms. After being stopped by a state trooper for not having his car lights on, Gerhardt, who smelled of marijuana, was accused of driving under the influence of cannabis. The subject was charged with a DUI after exhibiting symptoms of intoxication during three administered standard sobriety examinations. Citing unreliability in the procedure, Gerhardt challenged the verdict, filing a motion for a Daubert-Lanigan hearing to question the validity of expert witness testimony against him.[5] His focal point was the dearth of scientific evidence in relation to field sobriety tests and marijuana impairment.[6]

The Massachusetts Supreme Judicial Court chose to concur with the claimant. To settle the debate, the legislature determined that field sobriety tests cannot be considered definitive; instead, due to their uncertain nature, the examinations should be merely utilized as a reference point within litigation framework. As an additional revision of statute, the jurisdiction clarified the power of its constabulary: “An officer is not permitted to offer an opinion that [certain] characteristics (bloodshot eyes, drowsiness, and lack of coordination) mean that the driver is under the influence of marijuana, [as] ascertaining whether a person is intoxicated risks transforming the police officer from a lay witness to an expert witness on the issue.”[7] In other words, the Supreme Court of the Commonwealth of Massachusetts ruled that roadside field sobriety tests cannot be viewed as conclusive evidence proving someone is driving under the influence of cannabis.[8]

As of June 2018, recreational marijuana is legal in nine states and medical marijuana is legal in thirty.[9] Over time, the drug’s popularity and acceptance will spread as it becomes less and less illicit; therefore, it is essential to develop a standardized, reliable measurement system.

While multiple testing methods exist, these are not without their shortcomings. For instance, available blood and urine tests for THC require search warrants, a finding of U.S. Supreme Court Case Missouri v. McNeely. If a warrant is not obtained, evidence is considered inadmissible due to civil rights infringement. During the time required to obtain a warrant, however, THC levels decay, along with the strength of the evidence. As a further safeguard, obtaining a search warrant is contingent upon probable cause, adding an additional legislative barrier to obtaining and analyzing an individual’s bodily fluids for a preponderance of the evidence. Requirements can only be avoided if an officer determines through a “totality of the circumstances” urgent analysis that waiting would “significantly undermine the efficiency of a search.”[10]

In marijuana legalization, recent cases emphasize the legal consequences of ambiguous marijuana laws and flaws within contemporary litigation framework. As of now, due to the complications of this legal issue, it remains unclear how jurisprudence will respond to increasing legislative concerns. However, every new case will continue to serve as a wake-up call to jurists, law enforcement, claimants, and defendants, transitioning into heightened sensitivity over legal shortcomings. The United States government must dedicate research dollars and time to develop an easy, straightforward device with standardized metrics for marijuana intoxication. Albeit late, placing focusing on this topic will help redefine marijuana’s scope within the legislature, as well as remedy current policies.

[1] Migoya, David. “Are You High? The Science of Testing for Marijuana Impairment Is Hazy, and Evolving.” The Denver Post, 17 Dec. 2017,

[2] “Comparing State DUI Laws.” Findlaw,

[3] National Institute on Drug Abuse. “Does Marijuana Use Affect Driving?” NIDA,

[4] Beirness, Douglas J., et al. “An Evaluation of Data from Drivers Arrested for Driving Under the Influence in Relation to Per Se Limits for Cannabis.” AAA Foundation, 14 June 2018,


[6] “Standard Field Sobriety Tests Cannot Measure Marijuana Impairment.” Lexipol, 25 June 2018,


[8] Relational Semantics, Inc., and RSI. “Mass Appellate Courts - Public Case Information.” Supreme Judicial Court and Appeals Court of Massachusetts,

[9] Berke, Melia Robinson Jeremy. “This Map Shows Every State That Has Legalized Marijuana.” Business Insider, 28 June 2018,

[10] Sherry F. Colb Sherry F. Colb. “The U.S. Supreme Court Rules That Blood Tests for Drunk Driving Suspects Require a Search Warrant: A Wise Decision?” Verdict Comments, 24 June 2013,