BOISE, Idaho (AP) — Lawmakers have approved a new administrative rule for Idaho's prison system designed to ensure secrecy surrounding the source of the state's lethal injection drugs.

It's not yet clear if the rule will interfere with an ongoing lawsuit brought by University of Idaho Professor Aliza Cover, who sued the Idaho Department of Correction seeking access to lethal injection documents under Idaho's Public Records law two years ago. Cover largely won at the state court level, but the department appealed and the Idaho Supreme Court is expected to hear the case at some point this year.

Like previous versions, the rule forbids the Idaho Department of Correction from disclosing “under any circumstance” information that department director Josh Tewalt determines could jeopardize the department's ability to carry out an execution. The new version also specifically forbids the release of information that could potentially identify both past and future suppliers of lethal injection drugs.

Cover, ACLU policy director Kathy Griesmyer and a lobbyist representing the Idaho Press Club testified against the rule on Wednesday, each telling lawmakers that they were concerned the rule limits government transparency.

“The Idaho Press Club looks critically at any policy that reduces transparency and potentially erodes the Idaho Public Records Act,” lobbyist Ken Burgess told lawmakers.

He said the rule gives prison officials “unprecedented discretion and authority,” and said the Idaho Press Club is worried that approving the rule sets a dangerous precedent for future rule changes.

But Idaho Department of Correction Director Josh Tewalt said the rule aims to ensure that the integrity of the execution process is maintained.

“Most details that anybody could want are already publicly available,” Tewalt said. But he said it was important for the state to protect the source of execution drugs from disclosure, because maintaining the department's access to the drugs is critical to the execution process.

Prison officials have maintained that releasing the source of execution drugs would potentially subject the source to negative attention or protests, potentially causing the source to no longer be willing to provide the lethal chemicals.

“This is a heavily litigated area,” Tewalt said. “We've had recent incidents across the country where you've had executions ... referred to as being ‘botched.’ ”

The Board of Correction decided to change the rule partly in response to the problems elsewhere, he said.

“Part of it, on our end, is an insistence on learning what we can from other people on what we can do” to ensure the integrity of the process, he said.

But Cover noted the rule seems to be in opposition to a judge's ruling last year, which directed the department to reveal the source of the lethal injection drugs used in a recent execution.

“Idahoans, whatever their view on the death penalty, have an interest in knowing how their officials are obtaining those drugs and how they are using taxpayer dollars,” she said. "It seems now the Board of Correction is seeking not to increase its transparency but to limit it further."