banner of Priorities and Strategies for Improving the Investigation, Use of Toxicology Results, and Prosecution of Drug-Impaired Driving Cases

Issue #1:  What are the major problems encountered in processing a drug-impaired driving case through the criminal justice system?

5.  There is no standardization of practices in toxicology laboratories supporting DUID programs.

As with comprehensive documentation by a DRE officer, good-quality forensic toxicology is an essential part of the prosecution of a DUID case. The toxicology lab provides analysis of the biological specimen collected during the investigation. The lab needs to test for the most frequently encountered drugs in these cases, and use an appropriate level of sensitivity. The presence of a drug in a biological specimen provides the link between the observations of the subject’s driving and behavior and their drug use. There is a lack of consistency in the range of drugs tested for between laboratories, and in the cut-offs or analytical thresholds used by labs. There is anecdotal evidence that some laboratories are using inappropriate practices for this kind of work.

Differences of opinion remain among toxicologists regarding whether blood or urine is the most appropriate specimen. The development of new on-site testing technology for drugs in oral fluids may offer additional options; however, this technology is immature and is therefore not suitable for forensic purposes at present

An additional barrier to the standardization of practices in toxicology laboratories supporting DUID programs is the poor communication between toxicology laboratories and DRE programs. As a consequence, areas of weakness in testing procedures are not identified, followed up on, or remedied. In addition important opportunities to refine and strengthen the DRE drug identification criteria7, and identify proficiency problems with individual officers are missed.

In light of these considerations, this panel recommends that:

  • DRE coordinators should have regular contact with labs performing testing in their cases. In an effort to determine reasons for discrepancies, the coordinators should follow up on cases where the evaluation and the driving cues indicate impairment but no drugs are detected by the lab.
  • Laboratories engaged in drug testing in support of DRE programs have not been identified. At the time of this meeting, no central registry, list, or quality control program existed. As a result of this meeting, that process has been started, and these laboratories are currently being surveyed to establish what their current practices are, and evidence-based best practices and guidelines are being developed to direct the development of more consistent methods, procedures, and protocols for DUID laboratory testing.
  • NHTSA should work with professional organizations in forensic and behavioral toxicology to sponsor the development of national guidelines for policies and procedures, and develop incentives for States to comply with these evidence-based best practices in terms of methods and procedures for DUID laboratory testing.
  • The IACP DRE Technical Advisory Panel (TAP) should promote more cooperation between laboratories and State coordinators, encouraging DRE managers to understand what methods and procedures that their laboratories are using. It should also be required that the DRE officer’s evaluation face-sheet (the summary sheet showing the specific symptoms of impairment and physiological markers) if not the entire arrest report, be forwarded to the laboratory with the sample. This will assist the laboratory to determine if the regular test battery is sufficient or if additional tests are required.

6.  There is no clear correlation between blood drug concentrations and impairment for many drugs.

In DUI cases involving alcohol, a clear understanding has developed over the past 50 years regarding the relationship between increasing blood alcohol concentration and impairment. Tolerance to the effects of alcohol have been well characterized. Morever, the limitations it places on expert testimony are consistent and generally accepted by toxicologists.

The same cannot be said for drugs. The amount of research carried out is significantly more limited, and in the case of recreational drug use, researchers cannot ethically administer the doses of drugs typically taken by regular users. Other confounding factors include the common practice of combined drug or drug and alcohol use, where the interactions are not well known or understood. Additionally many drugs, particularly stimulants and narcotics, have markedly different effects in the acute phase from the later or withdrawal phases, even though the concentrations may be similar.

These limitations are a challenge. However research on this topic must continue and should be supported by laboratories, universities, drug companies, and funding agencies. This area of research is currently neglected. Because of these limitations, standard approaches to DUI prosecution that work well for alcohol, where there is a known relationship between alcohol concentration and impairment, may not be the optimum approach for DUID. Alternatives such as drug per se statutes, particularly for illicit drugs that are illegal in all circumstances, should be considered.

Accordingly, the panel recommends as follows:

  • The limitations of the current state of scientific knowledge make it critical that the toxicological findings be integrated with, and complemented by, findings from a DRE examination of the subject, SFSTs, and observations of the subjects driving and behavior in DUID cases.
  • Driving simulator, and on-road driving studies of illicit, prescription, and over-the-counter medications need to be funded and conducted, and must include quantitative toxicological testing of blood samples.
  • States should adopt drug per se provisions to complement existing statutes on drug and alcohol affected drivers.

rule line

7 The DRE program is based on a trained officer’s ability to identify the categories of drugs responsible for an individual’s impairment, based on physiological symptoms such as pulse, blood pressure, pupil size, horizontal and vertical nystagmus, muscle tone, and performance in field sobriety tests.