The Alabama Department of Corrections has prepared but not finalized a protocol for executing inmates by nitrogen hypoxia, an attorney for the department said during a Monday morning hearing.

The statement came during a hearing in the case of Alan Eugene Miller, the next person scheduled to be executed by the state of Alabama. Such a protocol would be the first of its kind, as to date, no one has been executed by nitrogen hypoxia and no state has approved a protocol for its use.

James Houts, attorney for ADOC, said it’s “very likely” that the state would be able to execute Miller by nitrogen hypoxia on his scheduled Sept. 22 execution date if the court moves them to, although he maintained that it is ADOC Commissioner John Hamm’s decision.

ADOC had gone as far as asking Miller to be fitted for a mask in preparation for executing him by nitrogen hypoxia, although Miller did not allow this, Houts said.

The supposed protocol has not been finalized or submitted in court records, and Miller’s attorneys were not aware that the state had developed a protocol for death by nitrogen hypoxia sufficient for use by Millers’ execution date later this month. ADOC hasn’t finalized the protocol because it must be “nested” into existing language for carrying out executions by lethal injection and electrocution.

“The protocol is there, but I won’t say it’s final,” Houts said.

Gov. Kay Ivey signed a bill into law approving nitrogen hypoxia as an alternative means of execution in 2018. The state has not executed anyone via nitrogen hypoxia to date as it had not developed a protocol for its use.

Parts of the protocol will be “public facing,” although other aspects will remain confidential, Houts said. He did not specify which parts of the protocol will be public record.

Mara Klebaner, Millers’ lead attorney, said his counsel has not received information about the supposed protocol and were worried that the state would be “rushing” the process if it were to execute Miller by nitrogen hypoxia on Sept. 22.