More people are getting behind the wheel after drinking alcohol and smoking pot, according to state troopers trained in drug recognition.
The Washington State Patrol warns that a combination of the two, even in moderation, can be dangerous.
"The trend that we're seeing out there is that people think it's OK to drink a little bit [and] smoke a little bit, but unfortunately the combination of the two amplifies the effects of the impairment," said Sgt. Courtney Stewart.
"It seems to be prevalent in the community that smokes a lot of marijuana that they really don't believe it's an impairing substance," she said.
As a Drug Recognition Expert (DRE), Sgt. Stewart is trained to identify impairment caused by seven categories of drugs, including cannabis.
Contact with a Drug Recognition Expert occurs after an arrest for driving under the influence has already taken place. A 12-step process is then used to determine what substance an individual might be impaired by, and to what extent.
Step 1: Determine if alcohol is involved. If an individual is clearly impaired by alcohol, it is unlikely that a Drug Recognition Expert is needed.
Step 2: Interview the arresting officer to better understand the circumstances that led to arrest. Was there a traffic collision? Was the driver speeding? Was the driver swerving on the roadway?
Step 3: Interview the suspect to determine whether there is an existing medical condition or other issue that may explain odd behavior.
Step 4: Eye Examination.
Step 5: Administer divided attention tests. Can the suspect follow directions? How well can they perform and concentrate on the task at hand?
Individuals who are high on marijuana typically perform poorly on a test called the Romberg Balance. The individual is asked to "tilt their head back and close their eyes," then estimate the passage of 30 seconds in their head.
"People would think that someone under the influence of marijuana would be really slow. They actually have a very fast internal clock," Sgt. Stewart said. "Someone under the influence [of pot] would estimate 30 seconds in 20 seconds."
Step 6: Vital signs. Take the suspect's pulse. A person who is under the influence of marijuana, for example, will have an elevated pulse.
Step 7: Dark room examination. Evaluate pupil dilation.
Step 8: Check muscle tone. Individuals on PCP, for example, may have rigid arms.
Step 9: Check for injection sites. A needle mark could indicate heroin use, for example.
Step 10: Interrogation.
Step 11: The Drug Recognition Expert forms an opinion and chooses a category of drug they believe the individual to be impaired by.
Step 12: Obtain a search warrant for a blood sample.
Stewart said several factors, including frequency of use, dosage, potency, and method of ingestion impact the level of impairment from marijuana.
According to the state patrol, "a person impaired by marijuana won't exhibit the same signs as a person 'drunk' on alcohol, but both are 'impaired.'"
Alcohol generally causes physical impairment, while marijuana tends to stay in the brain. Those under the influence of both would like suffer the amplified effects of both, simultaneously.
The Washington Traffic Safety Commission's "Drive High Get a DUI" campaign kicked off statewide Wednesday and will continue through Labor Day.