Psychopharmacology (Berl). 2012 October; 223(4): 439-446. This study finds that Standardized Field Sobriety Tests are only mildly sensitive to impairment from cannabis in heavy users. THC produced impairment on SFST performance in 30-50% of participants.
Drug Recognition Experts
State of Maryland v. Charles David Brightful, et al, No. K-10-04-259, Circuit Court for Carroll County, MD March 5, 2012
The Circuit Court for Carroll County, Maryland held that DRE evidence should be excluded. The court held that identification and classification by DREs “is not generally accepted as valid and reliable in the relevant scientific community.” See the opinion for a summary of expert testimony regarding DRE examinations which raises questions about the accuracy of …
Expert Testimony Regarding Impairment
Shea Denning of the UNC School of Government discusses the adoption of Rule 702(a1) and the admissibility of HGN and DRE evidence. For additional information, contact Shea Denning. She is available as a resource on this topic.
Do Delta9-Tetrahydrocannabinol Concentrations Indicate Recent Use in Chronic Cannabis Users?
Addiction. 2009 December: 104(12):2040-2048. This study finds that THC concentrations persist in whole blood multiple days after drug discontinuation in heavy chronic cannabis users.
Burton v. Kentucky, 300 S.W.3d 126 (Ky. 2009)
Testimony from a DRE was improper where the DRE did not personally observe the defendant but instead based his opinion on review of records.
Priorities and Strategies for Improving the Investigation, Use of Toxicology Results, and Prosecution of Drug-Impaired Driving Cases
2004 National Highway Traffic Safety Administration (NHTSA) publication targeted to prosecutors. The first section details some of the major problems with prosecuting drug impaired driving cases, such as the lack of any clear correlation between blood drug concentrations and impairment for many drugs (p. 8).