Almost four years after legalizing the recreational use of marijuana, Washington law enforcement continues to use blood tests to help determine a driver’s level of impairment in marijuana-related DUI cases, because it’s all they have.

Not only is it a slow process—for both suspect and police—but it’s also inaccurate for determining when marijuana was used and whether or not the driver was even impaired.

“There really is no definitive test for that,” said Moe Spencer, a marijuana criminal defense attorney. “It’s all a guessing game.”

The legal limit for marijuana in the state of Washington has been five nanograms of THC per milliliter of blood since it was first legalized for recreational use. While some argue that the limit is too low, Spencer consistently argues that “it’s just going to show how much is in your system” at the time blood was drawn, which is typically long after the traffic stop.

Because of the way marijuana is metabolized in the body, toxicologists can sometimes find traces of it a month after it was ingested, Spencer said.

“If you pumped my stomach and saw that I had a ham and cheese sandwich, and the report verifies that, it won’t say that the ham and cheese sandwich affected me or gave me the runs,” Spencer said as an example of what the blood tests actually do. “A blood test will never, ever, tell you when it [marijuana] was ingested.”

And in no case is the number from the test results ever going to be 100 percent accurate, according to Brianna Peterson, manager of the Washington State Patrol Toxicology Laboratory Manager.

“The concentration in the blood was probably much higher at the time of driving,” she said.

Lt. Rob Sharpe, section commander of the drug evaluation program for the Washington State Patrol, said the amount and quality of training drug recognition experts (DREs) go through provides solid evidence for officers to make an informed decision as to whether or not they should take a driver off the road.

“Your arrest should stand up without a breathe or blood test,” said Sgt. RAY? Cedeno of the Ellensburg Police Department.

To many officers the blood-test results are just a number to back up their observations. That’s why so many DUI cases—whether from marijuana, alcohol, or controlled substances—are heavily based upon officers’ observations from the standard field sobriety test (SFST).

The SFST is the most common way for officers to determine whether a driver is impaired. It includes a series of three tests: following the light with your eyes, the walk-and- turn, and the one-leg stand test.

The American Automobile Association recently released a study comparing the DRE test results of 602 drivers found with only marijuana in their system, against 349 volunteers who were sober. One of the eye-opening findings was that only 55.5 percent of the sober participants passed the walk-and-turn test perfectly. While drivers under the influence of

While drivers under the influence of marijuana did do considerably worse at the test, it supports those who contend that the level of THC in the blood should not be a determining factor.

The study also notes that some of the 80 percent who failed the SFST were found to be below the five-nanogram marijuana limit, while 30 percent of the people who passed the test were also found to have marijuana in their system of one nanogram or more.

Typically, medical marijuana users will frequently test higher than five nanograms, whether or not they’ve recently ingested.

The Washington Traffic Safety Commission has noticed a spike in deadly crashes where the driver tested positive for marijuana. The commission’s data shows that from 2013 to 2014, this statistic increased by 48 percent. That same year

Washington rolled out its “Target Zero” plan, which aims for zero highway traffic deaths by the year 2030.

For the Ellensburg Police Department (EPD), DUIs related to marijuana-impaired driving have not increased since the department started tracking it in 2014, even though it doesn’t count marijuana-related DUIs as a separate statistic.

It’s for that reason, along with Ellensburg's close proximity to a Washington State Patrol office and the Kittitas County Sheriff’s Office that Capt. Dan Hansberry of the EPD doesn't see the need to have a drug recognition expert on staff.

“If Ellensburg needs a DRE we will share any resources,” said Sgt. Mark Crandall, DRE/ SFST State Program coordinator. The Kittitas County Sheriff's Department is also mandated to share its resources.

Either way, a DRE is not needed for an officer to make an arrest, because “it's impossible to have a DRE at every arrest,” Crandall said, but it does put a heavier burden on the arresting officer.

The DRE program costs about $3,000 per officer. The Washington Traffic Safety Commission puts out grants to pay for the cost of the classes, Crandall said, but the department sponsoring the officer fronts the cost of living while the officer is training, along with on-duty time, gas, and travel.

A marijuana breathalyzer could change the game, as it would better pinpoint how recently marijuana was ingested.

There are such devices on the market but many authorities, including the WSP, believe they haven’t been thoroughly tested.

So until that day comes, Washington’s public safety officers say they’re comfortable continuing to use the blood tests.