Police and prosecutors around Virginia will have to change the way they handle marijuana cases after a warning issued late Thursday by the director of the Department of Forensic Science.

Linda Jackson sent a letter to "all agencies serviced by the DFS laboratories" warning that the state labs' testing capabilities are not sufficient to comply with a new state law.

"It's important for them to understand what the limitations of our testing are, so that they can make appropriate decisions in the criminal justice system," Jackson told the I-Team. "I definitely don't want anyone to go to jail if they were not breaking some law."

The move came the same day a News4 I-Team investigation revealed a two-fold problem driven by the rapid growth of hemp-derived products, like CBD, and state legislatures' rush to pass laws clarifying their legality.

An investigation by the I-Team revealed field tests used by law enforcement throughout D.C., Maryland, Virginia and around the country to identify marijuana also turn positive when testing CBD products. The tests merely detect the presence of cannabinoids and cannot tell which are ones present.

The I-Team reached out to several companies that make police field tests currently in use; none responded to our questions.

"The current marijuana field tests (Duquenois-Levine) approved by DFS are only capable of presumptively identifying Cannabis Sativa plant material; thus [they] cannot distinguish marijuana from industrial hemp," Jackson wrote. She indicated DFS is in the process of validating a different field test that may have that capability.

An additional concern stems from Virginia's new definition of marijuana, enacted in March following action from the state legislature. The new definition legalizes hemp-derived products like CBD, as long as they only have trace amounts of tetrahydrocannabinol (THC) no greater than 0.3 percent. THC is the component of marijuana that can get users high.

But currently, the state's forensic labs can only measure the THC percentage in oils; they're still working on establishing a quantitative lab test to measure the amount of THC in plant material, edibles and other products.

Jackson told the I-Team she expects to have the new quantitative tests up and running later this summer. In the meantime, the lab will only be able to tell if products contain THC, not the specific amount, which would determine whether the product complies with the new state law.

Once the labs develop that capability, it will be used to test evidence from cases where the plant material is "packaged and labeled as a hemp product" or if the defendant claims the product is in compliance with the new law.

"Because it's a time consuming test to do that quantitation to determine the concentration of THC, we don't want to do it necessarily if it's not required," Jackson told the I-Team.

Jackson says the lab is currently holding any cases where the need for quantitative testing may be an issue until those tests are able to be completed. She was aware of the coming changes to the law during the legislative process, however the impact the law would have and the need for additional testing capabilities was not immediately clear.

"The new law has definitely complicated all of this," Jackson said. "We are still working to make sure that we understand all of the definitions so that we are providing the appropriate types of tests."

She said the current language in the law still leaves some questions unanswered — for example, whether to consider an evidence sample of plant material as a finished product if it's packaged with branding as hemp-derived CBD. She said those kinds of questions will need to be answered by attorneys and legislators, not by the chemists in the state lab.