Cover: Countering Drug-Impaired Driving

Countering Drug-Impaired Driving

Addressing the Complexities of Gathering and Presenting Evidence in Drug-Impaired Driving Cases

Published May 7, 2020

by Camille Gourdet, Michael J. D. Vermeer, Michael G. Planty, Duren Banks, Dulani Woods, Brian A. Jackson

Download Free Electronic Document

FormatFile SizeNotes
PDF file 0.4 MB

Use Adobe Acrobat Reader version 10 or higher for the best experience.

Research Questions

  1. What challenges do law enforcement, toxicologists, and prosecutors face in identifying and prosecuting drug-impaired driving cases, and how can these challenges be addressed?
  2. What are the high-priority needs associated with drug-impaired driving cases?

Although alcohol-related impaired driving continues to be the primary cause of fatal automobile accidents in the United States, drug-impaired driving has emerged as a growing threat to public safety. Identifying and prosecuting cases of driving under the influence of drugs (DUID) requires the engagement of three important actors within the criminal justice system: law enforcement, forensic toxicologists, and prosecutors. Each of these actors plays a crucial role in gathering, interpreting, or presenting evidence of drug-impaired driving to build a successful case. Meticulous observational and chemical evidence collection and skilled, simple interpretation of this evidence is particularly important in a DUID case because such cases can be more complex and difficult to prove than alcohol-related impaired driving cases. Although blood alcohol concentration levels have been established and accepted as reliable and valid evidence of alcohol-impaired driving, no equivalent technique yet exists that correlates an amount of a drug in the body with the degree of drug-related impairment. To examine this issue, RTI International and the RAND Corporation convened a two-day workshop. The participants discussed the challenges, opportunities, and complexities faced by law enforcement, forensic toxicologists, and prosecutors in their roles collecting, interpreting, and presenting evidence in cases of driving under the influence of drugs. Using these discussions, the panel members identified and ranked needs for law enforcement, forensic toxicologists, and prosecutors to successfully identify and prosecute DUID cases. This report provides the prioritized list of needs and accompanying context from the discussion that resulted from this effort.

Key Findings

Participants stressed that detecting drug-induced impairment is critically important

  • Several useful tools exist that gather adequate evidence to identify DUID. These tools include specialized officer training, standardized field sobriety tests, roadside chemical testing, and subsequent toxicological screening. However, each of the available tools might be insufficient on its own to prove impairment and each comes with benefits and drawbacks.

Law enforcement officers need tools to enhance their ability to collect evidence to detect drug-related impairment

  • Specifically, officers need rigorous research to establish standardized, DUID-specific observational field tests that more law enforcement officers can be trained to use; protocols that can result in more-timely blood draws; considerations of whether electronic warrants can make the evidence-gathering stage of a case more efficient; and the proportion of law enforcement that should have advanced training in detecting drug-related impairment.

Forensic toxicologists need research to identify gaps in resources

  • Forensic toxicologists need research that can (1) help identify the gaps in resources, standards, or capability that might be preventing them from delivering adequate, reliable, and timely results in some jurisdictions and (2) describe the impact on justice and due process of not investing sufficient resources into toxicology testing.

Prosecutors need research that identifies successful means to address the complexity of DUID cases

  • There is a need to identify best practices for successfully prosecuting cases in the event that a suspect refuses to consent to observational or chemical tests. Prosecutors need mechanisms to increase DUID-specific training for themselves and court preparation for law enforcement and forensic toxicologists. Research also is needed to better understand the resulting risks and benefits to DUID cases of recent changes to implied consent laws.


  • Identify the likely benefits of having the right number of officers with specialized training in identifying drug impairment.
  • Add more observational tests to the standard field sobriety testing battery.
  • Conduct research to identify the barriers to adoption of electronic warrants and the costs, risks, and benefits of implementation.
  • Identify the costs, risks, and benefits of alternative phlebotomy approaches (e.g., officer training, contracts).
  • Collect detailed data on the effectiveness of DUID field sobriety tests when used for actual DUID cases and use those data to conduct additional research.
  • Develop and validate training to boost the confidence of officers when testifying.
  • Identify the gaps in resources and potential funding sources that could bring labs up to the required level of capability.
  • Promote and improve access to interpretive DUID training for toxicologists.
  • Identify the impacts and risks to justice and due process of not investing sufficient resources into toxicology testing.
  • Collect solutions that could increase access to training on litigating DUID cases.
  • Collect and identify critical research areas for DUID cases.
  • Identify best practices for dealing with refusals of testing.
  • Highlight the risks and benefits of changing implied consent laws and implementing other possible solutions, such as e-warrants.

Research conducted by

The research described in this report was prepared for the National Institute of Justice (NIJ) and conducted by the Justice Policy Program within RAND Social and Economic Well-Being.

This report is part of the RAND research report series. RAND reports present research findings and objective analysis that address the challenges facing the public and private sectors. All RAND reports undergo rigorous peer review to ensure high standards for research quality and objectivity.

This document and trademark(s) contained herein are protected by law. This representation of RAND intellectual property is provided for noncommercial use only. Unauthorized posting of this publication online is prohibited; linking directly to this product page is encouraged. Permission is required from RAND to reproduce, or reuse in another form, any of its research documents for commercial purposes. For information on reprint and reuse permissions, please visit

RAND is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.