Drug-impaired driving investigations often rely on several types of evidence. Unlike an alcohol-related DWI investigation, where a breath test can measure alcohol concentration, there is no single roadside measurement that establishes impairment by every type of drug. Officers may instead consider driving behavior, physical observations, field sobriety testing, specialized drug evaluations, and chemical test results.
Minnesota’s driving while impaired (DWI) laws apply to drugs as well as alcohol. Driving while impaired by drugs can result in criminal and driver’s license consequences. Understanding how this evidence is collected can help Lake Elmo drivers better understand the allegations against them.
How a Drug DWI Investigation Begins in Lake Elmo
A traffic stop generally must have an individualized lawful basis. An officer may observe weaving, unusual speed changes, traffic violations, or other driving behavior before initiating a stop.
After making contact with the driver, an officer may document speech, coordination, responses to questions, eye appearance, and other possible signs of impairment. The officer may also request field sobriety tests, which are roadside exercises used to evaluate balance, coordination, attention, and other physical responses.
What Field Sobriety Tests May Be Used?
Common standardized field sobriety tests include:
- Horizontal gaze nystagmus: An officer observes involuntary eye movements while the person follows a moving object.
- Walk-and-turn: The person follows instructions while walking heel-to-toe along a line.
- One-leg stand: The person balances on one leg while following instructions.
These standardized tests are based on protocols developed by the National Highway Traffic Safety Administration (NHTSA), a federal agency responsible for vehicle and roadway safety programs. The way a test was administered, the instructions given, and the conditions at the scene can affect the significance of the results.
How Drug Recognition Evaluations Work
When drug impairment is suspected, a Drug Recognition Evaluator (DRE) may become involved. A DRE is a law enforcement officer with specialized training in evaluating whether observed impairment may be associated with drugs rather than, or in addition to, alcohol.
A drug recognition evaluation follows a structured process that may include examining the driver’s eyes, checking certain vital signs, conducting divided-attention tests, making physical observations, and asking about possible drug or medication use. Divided-attention tests require a person to perform physical and mental tasks at the same time.
The DRE uses these observations to form an opinion about possible drug impairment. An attorney can review whether the evaluation followed applicable procedures, whether observations were documented consistently, and how the conclusions compare with other evidence.
Blood and Urine Testing in a Minnesota Drug DWI Case
Chemical testing means analyzing a biological sample, such as blood or urine, for drugs or substances produced as the body processes them. Minnesota’s implied consent law provides a legal framework for chemical testing in impaired-driving cases.
When an officer has probable cause to suspect drug impairment, a blood or urine test may be sought. Probable cause means there are facts and circumstances that provide a reasonable basis to believe an impaired-driving offense occurred. Minnesota generally requires a search warrant or a recognized exception to the warrant requirement before blood or urine can be collected. A search warrant is a court order authorizing law enforcement to obtain specified evidence.
What Happens If a Driver Refuses Testing?
The consequences of refusing chemical testing depend on the type of test and whether the legal requirements for requesting it were satisfied. Test refusal can carry criminal or driver’s license consequences in circumstances covered by Minnesota law. The type of test, whether a warrant was obtained, and how the request was made may therefore be relevant.
What Evidence Can Be Reviewed?
A drug DWI investigation can produce evidence at several stages. An attorney may examine:
- The legal basis for the traffic stop.
- The officer’s observations and reports.
- How field sobriety tests were administered.
- Whether a DRE evaluation followed applicable procedures.
- Whether blood or urine testing satisfied legal requirements.
- How biological samples were collected, stored, transferred, and tested.
- Whether laboratory findings support the allegation of impairment.
The handling of a biological sample from collection through testing is known as the chain of custody. This refers to documentation showing who possessed or handled the evidence and how it was stored and transferred.
For drivers in Lake Elmo, Woodbury, or elsewhere in Washington County, understanding how the evidence was developed can help clarify the issues involved in a drug-impaired-driving charge. A lawyer can review the stop, officer observations, DRE evaluation, chemical testing, and other evidence that may affect the case.
Coodin Law Office, LLC is a Minnesota law office that represents people facing DWI and other criminal charges. If you have been charged with drug-impaired driving, contact our law office to discuss your circumstances with an attorney.