Beyond a confession that a bag of cannabis is actually marijuana and not hemp — or until the state finds a definitive test to determine which is which — State Attorney Jack Campbell’s office is putting a hold on prosecuting pot cases.

“This office will no longer be charging people with possession of cannabis absent a confession to what the substance is or testing by a lab that can meet the evidentiary standards,” he wrote in a Tuesday letter to law enforcement officials.

“I know this is a significant change in the law and would caution you in making arrests when these issues are present.”

The federal government’s 2018 Farm Bill legalized hemp, as did the Florida Legislature, allowing people to lawfully possess cannabis with minuscule amounts of THC, the psychoactive ingredient in marijuana that produces a high.

At issue is the current difficulty statewide determining whether hemp products, which look, smell and come from the same family as marijuana, contain .3% or less THC.

The prevalence of hemp products — everything from soaps, to hand creams and gummies which contain the non-euphoric chemical CBD, cannabidiol — have exploded onto the self-care healing market and represent a multi-billion dollar growing industry.

But law enforcement technology has not caught up with a way to test the amount of THC in products. Right now, roadside tests and Florida Department of Law Enforcement labs can only test whether THC is present.

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Even more troublesome is that roadside techniques for developing probable cause rely on smell and look, two things that are identical in hemp and marijuana.

“Hemp products look and smell exactly like marijuana products,” Campbell wrote. “Much of the search and seizure law hinges on either the officer’s or K9’s ability to smell. This seems to now be in significant doubt. I would suggest that your officers and deputies no longer rely purely on their identification of believed cannabis.”

FDLE has been working to secure a test that can quantify the amount of THC. The Florida Department of Agriculture, which regulates medical marijuana and Florida’s burgeoning hemp program, does not have a way to do testing.

A validated test that can be backed up by expert testimony in court is essential for illegal marijuana prosecutions to go forward, Campbell wrote.

There are labs around the country that conduct marijuana testing, but Campbell cautioned that bringing experts from private companies to court to testify could created a financial burden that outweighs prosecution.

“The current posture is that no public or private labs in Florida can do this dispositive testing,” he wrote. “We are hoping to get a presumptive test that will work in Florida, but we don’t have it yet.”

Representatives with the Tallahassee Police Department acknowledged receiving Campbell's letter but said they would continue to uphold the law.

"TPD wants to remind citizens that while hemp is legal, marijuana is still illegal in the State of Florida," TPD spokesman Damon Miller said in an emailed statement. "TPD will continue investigating suspected marijuana cases In the event that probable cause is established, TPD will seize the evidence for potential prosecution."

The Leon County Sheriff’s Office acknowledged the similarities between hemp and marijuana in guidelines developed in early July.

To help deputies determine probable cause in situations where they suspect marijuana possession, the guidelines suggest noting the criminal record of an individual, the person’s demeanor, signs of marijuana impairment or the presence of drug paraphernalia.

Campbell said there will be some exceptions in which illegal marijuana cases will still be pursued.

"But we can’t do it without being able to prove that it’s legal marijuana,” he said in an interview with the Democrat.

Contact Karl Etters at ketters@tallahassee.com or @KarlEtters on Twitter