Thursday, March 23, 2023

Cops use field drug tests despite possible inaccuracies

Field drug testing kits are being used regularly in police work, but how reliable are these tests?

Ashley Nichols, a narcotics investigator, for the Williamsburg Police Department said most of the tests are used for marijuana. 

Officers will use the kits when they find substances they suspect could be pot.

The way it works, Nichols said, is that the officer places the particle of the suspected substance into the kit. The kit has three glass tubes inside and after placing the substance into the kit, the officer will break the first tube and release a purple fluid. Next, the second and third tubes are broken.

Once all three are broken, the officer looks to see if the purple color separates to create a gray color, indicating the substance contains levels of tetrahydrocannabinol, which is the active ingredient in cannabis.

In James City County, police spokeswoman Stephanie Williams said officers use marijuana field tests most frequently. Tests for other drugs are also available but she said that officers don’t use these in the field because drugs other than marijuana can contain fentanyl more frequently which can be dangerous for officers.

In Williamsburg, officers use other test kits for heroin and cocaine but when using field tests for those drugs, officers will send them to a lab to be tested again for accuracy. With marijuana field tests though, Nichols said usually the results from the kits are enough evidence to use in court.

However, a 1974 study from the National Bureau of Standards warned against using those kits as “sole evidence for identification of a narcotic or drug of abuse.

Just four years later, the Department of Justice concurred field tests should not be used as evidence and the field tests which are still in use today should remain inadmissible.

Most recently, a report in 2014 from the Las Vegas Metropolitan Police Department submitted to the U.S. Department of Justice showed the field kits can often have false positive results.

Yet a study from RTI International, a nonprofit research group from North Carolina, found that nine out of 10 jurisdictions in the nation accept guilty pleas based on field tests alone.

Marijuana arrests are growing in both Williamsburg and James City County, with data showing a 46 percent and 43 percent rise in arrests respectively in the past five years. Nichols said marijuana field tests are used weekly by most officers and often lead to arrests.

The Commonwealth’s Attorney’s Office did not immediately respond for comment on whether field tests were used as evidence in Williamsburg-James City County.

Nichols said the kits used by their department come from the U.S. Department of Forensic Science and that she has never seen one of the kits result in a false positive.

“We use the kits that are approved and supplied by the DFS,” Nichols said when asked why departments still use the tests despite possible room for error.

The U.S. Department of Forensic Science did not immediately respond for comment.

Nichols said when someone is charged in relation to marijuana, they sign a form saying that they can send the sample to a laboratory to be tested in addition to the field test if the defendant wants. But, police will use the results from the field test unless the defendant requests that it be sent to a lab for additional testing.

If the results from a lab test showed negative for illegal substances, Nichols said those results would also be presented in court.

Nichols did not have an exact number for how frequently defendants choose to submit the substances for additional testing.

“It is up to the suspect and the defense attorney to decide if they want to submit marijuana for lab analysis,” she said.

But the results of those field tests, which have been questioned by researchers, are playing a role before they even enter a courtroom.

“There’s a couple of reasons we just use the field field test,” she said. “Some of them are to serve an investigative purpose, and some is just to use probable cause for an arrest. If it does test positive in a field test, it’s enough probable cause.”

Alexa Doiron
Alexa Doiron
Alexa Doiron is a multimedia reporter for WYDaily. She graduated from Roanoke College and is currently working on a master’s degree in English at Virginia Commonwealth University. Alexa was born and raised in Williamsburg and enjoys writing stories about local flair. She began her career in journalism at the Warhill High School newspaper and, eight years later, still loves it. After working as a news editor in Blacksburg, Va., Alexa missed Williamsburg and decided to come back home. In her free time, she enjoys reading Jane Austen and playing with her puppy, Poe. Alexa can be reached at

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