AUGUSTA, Ga. (AP) — Prosecuting drivers under the influence of synthetic cannabinoid products, or spice, is proving to be a challenge in Georgia, authorities said.

Changes in the drug are outpacing the crime lab's ability to test for it, The Augusta Chronicle reported.

Spice has an effect on drivers that's almost identical to marijuana, said Richmond County sheriff's Sgt. Danny Whitehead, who is a supervisor on the department's DUI task force.

The slowed reaction time and general lack of awareness make driving dangerous, but getting users off the street through court cases can be difficult because of a lack of proof, authorities said.

Spice is a chemical drug that is constantly evolving, Whitehead said. He said that every time one version becomes illegal, producers alter it slightly, making it legal again. The changes can make it difficult to test for the drug.

In February, the U.S. Drug Enforcement Agency extended a temporary order that makes five of the chemicals used to produce spice illegal through Aug. 29.

Georgia law makes about 90 percent of synthetic cannabinoid products illegal, Georgia Bureau of Investigation spokesman John Bankhead said.

Currently, the GBI can test for some versions of spice and are expanding testing capabilities, Bankhead said.