Law enforcement has been trying to overcome obstacles with screening motorists for drug-impaired driving after states have legalized marijuana for medical and recreational use and the opioid crisis has grown. Unlike drunk driving, there are no breath-testing devices to measure drivers for drug impairment. Pennsylvania and another eight other states, however, have started programs allowing police to draw blood from motorists to detect drug-impaired driving.
Police may suspect that a motorist is driving while impaired based on their driving patterns, their appearance, a field sobriety test and their interaction with the police officer who made the stop. A blood test is intended to determine which substance is causing the impairment. Law enforcement officials have looked for ways to quickly draw blood to avoid losing it effectiveness as evidence. Like alcohol, the psychoactive compound in marijuana and drugs such as heroin metabolize quickly in a person's body.
When police draw blood at a traffic stop, instead of taking motorists to a health facility, it decreases the time that drugs metabolize. This also decreases costs by not paying phlebotomists and hospitals to draw blood. It may also reduce the time that a driver remains in police custody after they are arrested.
Police must receive training and certification before they can take blood from drivers. However, one DUI attorney has questioned whether blood should be drawn outside of a medical facility because of the risk of infection and disease and the lack of concern about pain reduction. Lawyers have also worried about the use of an e-warrant process that allows the issuance of warrants by telephone, video or electronic affidavits. They questioned whether the judges read the e-warrants with the scrutiny expected for this testing. Any testing must comply with a person's constitutional protections against illegal search and seizure.