Virginia Agency Purchases Field Test Kits to Discern Hemp From Illegal Cannabis
The 4-AP field test kit measures the ratio of CBD to THC in cannabis.
Virginia Department of Forensic Science

Virginia Agency Purchases Field Test Kits to Discern Hemp From Illegal Cannabis

The 4-AP test will be distributed to law enforcement agencies to measure the ratio of THC to CBD in the plant in question.

December 9, 2019

As local law enforcement agencies continue struggling to decipher the difference between hemp and tetrahydrocannabinol (THC)-rich cannabis, the state of Virginia is hoping to quell the issue with a new field test kit.

The Virginia Department of Forensic Science recently purchased 16,150 Cannabis Typification testing kits—otherwise known as the 4-AP test—to distribute to police departments across the state. 

While the test cannot determine the exact levels of cannabinol (CBD) and THC in cannabis, it does measure the ratio of the two cannabinoids to ascertain whether the plant is hemp or THC-rich cannabis.

The test turns different colors based on the ratio of the cannabinoids in the plant sample. If the concentration of THC is more than CBD, the liquid in the kit turns blue, indicating it is illegal and needs to be sent to the laboratory for further testing. If the plant has more CBD than THC, the liquid in the kit turns pink, indicating it doesn’t need lab testing.

The test needs to be used in conjunction with the Duquenois-Levine field test, which is widely used by police to identify cannabis. If that test comes back positive, officers can use the 4-AP test to narrow down whether the plant is most likely THC-rich cannabis or hemp.

Linda Jackson, the director of the Virginia Department of Forensic Science, says the Duquenois-Levine test is still an important part of the equation. 

“We did test [the 4-AP test] on some non-cannabis types of plants, and it does give a light blue result with oregano, which could be confused with the result for marijuana. That’s why in our instructions, we’re telling law enforcement to use Duquenois-Levine test first,” Jackson says.

The test is not approved as a field test by the Virginia Register of Regulations, meaning it can’t be used for testimony; it can, however, be useful for investigation.

The kits were purchased for $97,500 with a grant from the Virginia Department of Criminal Justice Services, and any law enforcement agency across the state can sign up to receive them.

“Virginia passed [its] hemp legislation in March of 2019, and so as soon as that legislation was signed, it became more difficult to determine whether cannabis was illegal or not,” Jackson says. “We just wanted to provide it as a tool for law enforcement for that purpose.”

It’s an issue law enforcement has been grappling with since hemp became legal, and especially since its interstate transport was made legal in October 2019 with the U.S. Department of Agriculture’s interim final hemp rule. Stories across the country have emerged in recent months about truckers facing felony charges for transporting hemp, including a high-profile case in New York where law enforcement touted a marijuana bust on social media—though the seized product allegedly is hemp. That case is still moving through courts.

The USDA and U.S. Department of Justice are reportedly working to develop a database that can track and share information on hemp production with law enforcement, according to IEG Policy. The first iteration of that system, however, may be far-off and rudimentary.

In the meantime, the kits used in Virginia provide a solution for officers looking to quickly discern between THC-rich cannabis and hemp.

Check out a video, courtesy of the Virginia Department of Forensic Science, outlining how the test works below.