CHICAGO (Reuters) - Ohio Governor John Kasich on Monday delayed nine scheduled executions because of a court battle being waged over the state’s lethal injection protocol.

FILE PHOTO - Ohio Governor and former presidential candidate John Kasich speaks to reporters after an event honoring the Cleveland Cavaliers, at the White House in Washington November 10, 2016. REUTERS/Kevin Lamarque

Kasich’s office said the delay was necessary because of the timing of a 6th U.S. Circuit Court of Appeals hearing on the state’s appeal of a court ruling that its execution process was unconstitutional.

The Cincinnati-based appeals court has scheduled oral arguments for June 14. The governor’s office said that meant postponing the planned May 10 execution of Ronald Phillips, who was sentenced to death for the 1993 rape and murder of his girlfriend’s 3-year-old daughter, and eight other executions scheduled in the months afterward.

Allen Bohnert, a federal public defender representing two of the inmates in the legal fight, could not be reached for comment on Monday.

At issue is an injunction issued by a lower court after it determined that it was likely that Ohio’s use of midazolam hydrochloride to render condemned inmates unconscious before two other drugs are administered in executions entailed a “substantial risk” of serious pain that violated their constitutional rights against cruel and unusual punishment.

Several U.S. states use midazolam in executions, including Oklahoma and Arizona, where witnesses said inmates appeared to twist in pain on death row gurneys.

Questions about the drug’s effectiveness were highlighted recently in Arkansas when it executed its fourth inmate in eight days before its supply of midazolam expired. Witnesses said the condemned man jerked and gasped for air for about 30 seconds a few minutes after his execution began.

Robert Dunham, executive director of the non-profit Death Penalty Information Center, said on Monday it was unclear if the appeals court case would ultimately resolve the debate over the use of the sedative in executions.

Death penalty states once used an anesthetic in their mixes until major pharmaceutical companies began banning sales to prison systems about six years ago because of ethical concerns.

In response, several states, including Ohio, turned to new mixes that included midazolam.

Monday’s postponement in Ohio marked the latest setback for death penalty supporters after executions in the Midwest state were set to resume in January 2017. There had been a three-year pause in executions because prison officials faced difficulties obtaining the needed drugs.

Ohio’s last execution took place in January 2014 when it put Dennis McGuire to death for the 1993 rape and murder of a pregnant woman.