The U.S. Drug Enforcement Agency has sent a letter to explain why THCA doesn’t meet the definition of legal hemp.

The letter is a response sent on May 13 from the DEA’s Chief Drug & Chemical Evaluation Section, Diversion Control Division, Terrence Boos, to Shane Pennington, cannabis lawyer and partner at law firm Porter Wright Morris & Arthur LLP, who requested the control status of tetrahydrocannabinolic acid (THCA) under the Controlled Substances Act (CSA) with a letter dated April 25.

The legal status of THCA under the CSA has been debated, as its federal compliance depends on several factors and the interpretation of the rules.

Unlike delta-9 THC, or simply THC, the main compound of cannabis with intoxicating effects, THCA, another compound of the same plant, hasn’t psychoactive properties when found in raw cannabis.

However, when THCA is heated through a process known as decarboxylation, it transforms into THC, which has intoxicating effects. This conversion can also happen when cannabis ages, as decarboxylation occurs at lower temperatures over a longer period, while higher temperatures speed up the process.