Oklahoma law enforcement could have a new way to confirm the presence of marijuana in impaired drivers by the end of 2018.

Cody McDonell, spokesman for the Oklahoma Highway Safety Office, said the state is working to establish a test that would allow law enforcement to swab the inside of a driver’s mouth to detect the presence of marijuana. It could be a reality by the end of the year, he said.

Oklahoma has not established a “per se” level for marijuana, such as the .08 percent limit for alcohol. The swab test would not measure how much THC a driver has in his or her bloodstream, but would give officers a “yes” or “no” answer on whether it was present, McDonell said.

“Basically what it does is it’s a portable test that gives them (law enforcement) probable cause to do further testing,” McDonell said.

The process to establish tests is in the early stages, he said.

As Oklahoma voters are set to consider State Question 788 in June, the state is considering a new wave of impaired driving that could possibly come with its passage.

SQ 788 would legalize medical marijuana in the state. Currently, the possession of marijuana is illegal. At least 30 states and Washington D.C. have passed laws legalizing or decriminalizing medical marijuana.

“We understand the reality that it might happen, so we’re kinda looking at how we’re gonna look at that,” McDonell said. “How are we gonna get the message to people — you can smoke now, but you can’t drive.”

The use of cannabidiol, also known as CBD, is allowed for use for some medical reasons in Oklahoma. The state authorized clinical trials for CBD for people 18 year or younger with severe forms of epilepsy in 2015. The age cap was removed and clinical trials were expanded for additional medical conditions in 2016.

Campaigns to combat impaired driving in Oklahoma have historically focused on alcohol. Now, the state is starting to see more drivers under the influence of marijuana, opioids and other drugs, McDonell said. Part of the challenge is changing the public’s perception on driving under the influence of marijuana.

“We’re going to have to shift what we’re testing for and how data is collected,” he said.

Most law enforcement agencies currently depend on their “drug recognition experts,” who are specially trained to identify people under the influence, McDonell said.

Washington, which made recreation pot use legal, has established a “per se” level for consumers. Like Oklahoma, California has not established a level, but depends mostly on drug recognition experts. However, some agencies there have devices to detect the presence of drugs.

Many agencies across the country use the swab test Oklahoma is considering.

McDonell said the OHSO isn’t for or against SQ 788, but they are against any form of impaired driving.

Drivers impaired by drugs are a growing problem in the state, he said.

April 20, or 4-20, is associated by some as a celebratory day for the consumption of marijuana.

On Friday, Oklahoma Highway Patrol troopers planned to set up a DUI checkpoint to stop drivers who may have consumed marijuana or other drugs. Other agencies across the state are also increasing patrols and sobriety checkpoints Friday.

Casey Roebuck, spokeswoman for the Tulsa County Sheriff’s Office, said the agency’s deputies are keeping a closer lookout for impaired drivers Friday. The department also has lent surrounding agencies some of their drug recognition experts, which TCSO has seven of.

Dwight Durant, a spokesman for OHP, said troopers will be looking for the odor of marijuana on drivers.

“That’s the main thing,” Durant said. “It’s just so obvious.”

In 2016, Oklahoma had 121 fatal drug-related car crashes, according to OHSO data. The data includes illegal and prescription drugs. In 2015, there were 75 fatal drug-related car crashes, the data shows.

“We’re not police looking to kill your high,” McDonell said. “We’re not condoning it, but if you decide to break the law today and go smoke weed, please don’t get behind the wheel and drive.”

An earlier version of this article stated “cannibas oil” is allowed for medical research in Oklahoma. It has been corrected to “cannabidiol.”