Law enforcement prepare to pull people over for pot behind the wheel

NAPERVILLE, Ill. (WLS) -- More than 300 police officers gathered in Naperville Thursday, hosted by AAA to highlight the challenges they say they'll face when recreational marijuana becomes legal on January 1, 2020.

The goal was to search for effective solutions to keep drivers who are impaired by pot off of the road.

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New technology and better police practices were all on the table as officers and deputies from Illinois prepare to pick up people smoking pot behind the wheel.

"Impairment is impairment, whether it's alcohol or any drug. It affects their ability to safely operate a motor vehicle," said Illinois Traffic Safety Resource Prosecutor Jennifer Cifaldi.

Cifaldi said for cops that means looking deeper than a wobbly walk down the white line.

"There's much more of an effect on the executive function versus physical motor skills," she said. "Can they remember what you just told them? Can they multitask? These are divided attention tests."

But exactly how to test for cannabis impairment behind the wheel is hotly debated, even as communities like Carol Stream pilot test saliva-based cannabis field sobriety kits.

"There's still a lot of science that needs to be developed. Everything is still in its preliminary stages," Cifaldi said.

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One of the biggest challenges for law enforcement, they said, is a race against time. Under the new law, officers have a strict time limit on when they can collect a blood sample. According to Master Patrol Officer Larry Brooks with the Decatur Police Department, blood is the best way to determine if someone has used cannabis in the last few hours and then got behind the wheel.

"It's active, it's in their system, it's not like in urine where it's going out of the system," Brooks said. "You know it's still actually psychoactive in their system."

Brooks is one of only 11 police officers in the state officially trained in phlebotomy, or drawing blood.

"The biggest problem is honestly the dissipation rate of cannabis. Because after they smoke, within that 90 minutes, it's almost gone out of their system, so you have a two hour window," he said.

Brooks said you do have a right to refuse a blood draw, and cannabis enforcement experts say that can make a case to prove impairment behind the wheel more difficult.