The bar just got higher for deputies to make marijuana arrests in Pinellas County.

Pinellas Sheriff Bob Gualtieri and Pinellas-Pasco State Attorney Bernie McCabe on Wednesday issued a memo cautioning deputies about making pot arrests in light of a new law legalizing a type of cannabis called hemp.

While the memo only applies to the county’s 820 or so deputies, some Pinellas County police departments have also raised the standards for their officers to make marijuana arrests since the state law went into effect July 1. Wednesday’s memo marks the first time the county’s top prosecutor has issued an official stance on which marijuana cases his office is willing to pursue.

“There’s just been some instances where cases were being made that were not prosecutable," McCabe said, “and the sheriff was unhappy with that and so was I.”

The memo spelled out these standards:

For creams and oils, the memo advises that deputies generally avoid making arrests unless the substance is in large amounts. Oils are typically consumed through vaporizer pens or e-cigarettes. In schools, where vaping is on the rise, deputies were advised to avoid making arrests and instead refer the student to administrators for discipline.

For cannabis-infused food products such as cookies or gummies, known as edibles, deputies were told to make no arrests, according to the memo.

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When it comes to plant material, deputies have a little more discretion under the new rules. Before the new law, marijuana had such unique properties that an officer could rely on smell and appearance to decide there was probable cause to make an arrest as opposed to, say, spotting white powder, which could be cocaine or crushed Aspirin.

However, legal hemp and illegal marijuana flower are indistinguishable by smell and appearance.

Deputies must cite factors beyond scent and appearance to make an arrest based on plant material, according to the memo. Those factors include behavior, how the plant is packaged and a subject’s prior criminal history.

“What you’re saying to the cops is you have discretion but you can no longer use the bright line rule,” the sheriff said, referring to a clearly defined standard.

The St. Petersburg and Clearwater Police Departments have already rolled out similar rules for plant material. In Pasco County, also under McCabe’s purview, sheriff’s spokesman Kevin Doll said officials there are reviewing Wednesday’s memo to decide how to move forward.

The cannabis enforcement changes arise from a legal quandary law enforcement faces over a bill passed by the Florida Legislature this year that sets up infrastructure for a statewide hemp program and paves the way for a legal CBD industry.

CBD is the compound found in hemp and marijuana that doesn’t get users high. THC, the stuff that does get users high, remains illegal unless prescribed by a doctor for medical use.

The problem for law enforcement is in the measurement.

Hemp-derived products still contain trace amounts of THC, so the new law allows up to 0.3 percent of the compound in products. But the field tests used by law enforcement can only determine the presence of THC, not the concentration.

Another layer of testing is done at labs across the state. As of this week, a testing method used by the Pinellas County Forensic Lab can largely determine the difference between hemp and marijuana, said lab director Reta Newman.

That makes some arrests possible as long as the substance is preserved for testing. However, the lab can’t test for edibles. In extreme cases, law enforcement can pay for those tests at a private lab, Newman said.

The remaining counties in the Tampa Bay area, and most across the state, rely on five Florida Department of Law Enforcement labs for testing. That agency is working on setting up the same testing process as Pinellas by spring 2020, said David Coffman, forensic services director for the state crime lab system.

Gualtieri said lawmakers should address what he sees as holes in the law to ensure enforcement is consistently applied.

“The laws should always be easily understood on both sides — those who are supposed to follow it and those who are supposed to enforce it," he said. "This is not one of those situations.”