1. Drug-Impaired Driving in the Age of Legalization
2017 STRATEGIC HIGHWAY SAFETY SUMMIT AND
AAA DRUGGED DRIVING SYMPOSIUM
Nathan Warren-Kigenyi
Manager of Traffic Safety Research & Analysis
AAA National Office ● Washington, DC

6. 817%
The Washington State Dept of Health / CDC Behavioral Risk Factor Surveillance System has been measuring the prevalence of marijuana use in the state since 2011 (asks about any use and number of days used in past 30).
The survey showed a small increase in the percent of the population that reported using marijuana at all.  It increased by somewhere in the ballpark of 2 percentage points from before legalization to after, but the increase in use was not nearly as large as the increase in prevalence among drivers in fatal crashes. 
This suggests (strictly speaking, does not actually prove, but in my opinion pretty strongly suggests) that in addition to more people using marijuana generally, the prevalence of driving shortly after using marijuana increased even more in the 1-2 years after legalization.

7. In 2014, 1 in 6 drivers involved in fatal crashes in Washington State had recently used marijuana

8. Marijuana Legalization Laws
November 2016
(D.C.)
States with marijuana per se blood limits
Colorado * ng/mL
Illinois ng/mL
Montana ng/mL
Washington ng/mL
Nevada ng/mL
Ohio ng/mL
Pennsylvania ng/mL
Legalized for recreational and medicinal use (8 states + D.C.)
Legalized for medicinal use only (20 states)
Not legal (22 states)
*In Colorado, 5 ng/mL = permissible inference a person was under the influence of drugs.

11. Better Alternative to Per Se Laws
What gets you pulled over
Results of a SFST
Opinion of a Drug Recognition Expert
Positive blood test for active THC

12. Reasons for Misinformation
Vocabulary Misuse
Dearth of Research
Internal Validity of Early Research
Federal vs. Street
Cannabis & DUI Arrest/Conviction Data
Cannabis & Crash Data
Peak THC Blood Levels ≠ Peak Impairment

13. Blood v. Brain THC Levels
Distribution of THC in the body. The distribution of THC after a single administration in plasma and body tissues. Note the ‘biphasic’ disappearance in plasma. The rapid phase (in minutes) indicates a rapid uptake of the drug by fat-containing tissues. The slow phase (in days) shows the release of THC by these tissues (Nahas, 1975). THC, tetrahydrocannabinol.

14. How often does drugged driving cause crashes?
Roadside drug tests not widely available
- (and no model specifications)
LE don't usually test for drugs if driver has BAC ≥ 0.08 because (1) enough evidence for a DUI charge and (2) cost and (3) time.
Crash involved drivers and poly-drug use
hard to know which substance had the greater effect
DATA

15. Data Barriers Report & Policy Recommendations
More & Better Data on drugged driving
Policy/Advocacy

16. Marijuana Legalization
AAA’s Position
Traffic Safety Implications
Medicinal Marijuana
Future Research and Considerations

18. Nathan Warren-Kigenyi
Thank You!
Nathan Warren-Kigenyi