Police officers in Maryland and around the country often use portable breath testing devices to determine whether or not a motorist is impaired by alcohol, but blood must be drawn to establish drug use. The U.S. Supreme Court has ruled that law enforcement must obtain search warrants before drawing blood, and the way police departments are meeting this requirement has many civil rights advocates worried. To speed up the process, 45 states allow police to obtain warrants by video, telephone, or affidavits sent electronically.
This has raised concerns because judges are expected to scrutinize warrant applications carefully to protect rights against unreasonable searches guaranteed by the Fourth Amendment, but most electronic search warrants are issued in a matter of minutes after only a cursory review. In some states, police speed up the process even further by using vans to conduct blood draws at the roadside rather than taking drugged driving suspects to a medical facility.
Police departments say that blood must be drawn quickly to establish narcotics use because many drugs that impair drivers metabolize quickly. Figures from the Governors Highway Safety Association suggest that the problem is serious and growing. According to the GHSA, almost 44 percent of the blood taken from drivers killed in fatal accidents in 2016 tested positive for drugs. That figure was 50 percent lower just 10 years ago. Experts say that this rise is due to laws passed in many states that permit the use of marijuana for medical or recreational purposes.
Experienced criminal defense attorneys may question the validity of blood evidence in marijuana impairment cases even when police have acted quickly. This is because there is no clear scientific link between impairment and THC levels in the blood. Researchers have found that long-term marijuana users may be unimpaired with THC levels that would leave casual smokers of the drug barely able to function.