Kentucky officials signaled Thursday they will change how prisoners are executed, opening the door to using a single drug instead of the current three-drug method that has been challenged by inmates who call it cruel and unusual punishment.

The Kentucky Justice Cabinet filed notice in Franklin Circuit Court that it would propose new regulations by July 24. The single-page motion does not say what changes will be made. The new method could be in place by late summer, allowing Kentucky to begin executions later this year.

Justice Cabinet spokeswoman Jennifer Brislin declined comment.

Franklin Circuit Judge Phillip Shepherd in April gave Kentucky 90 days to make changes or face a trial to defend the three-drug method. Shepherd said if Kentucky adopts a new regulation allowing for a one-drug execution _ similar to what is done in Ohio, Arizona and other states _ any claims of cruel and unusual punishment by the inmates "will be rendered moot."

The battle over Kentucky's lethal injection method has been going on for more than a year and a half. The judge's ruling and Kentucky's decision comes just months after the American Bar Association issued a report calling for a moratorium on executions in Kentucky, in part because of the number of cases overturned since the reinstatement of the death penalty in 1976.

At least seven states use a single drug to carry out executions. Three states _ Idaho, Washington and South Dakota _ give an option to use more than one drug. In the last week, Missouri became the first state to switch to propofol, the same anesthetic that caused the overdose death of pop star Michael Jackson.

Kentucky's current method calls for a single drug or combination of drugs. The state last used sodium thiopental, pancurionium bromide and potassium chloride, a combination similar to the one used by Georgia and some other states.

When the U.S. Supreme Court upheld Kentucky's three-drug method in 2007, Shepherd wrote, a one-drug method was still untested. That's no longer the case. Since then, states have successfully used a single drug for executions, creating what Shepherd called a safer alternative for lethal injections.

To change the regulations, Kentucky officials must submit to the state a new execution method, which is made public. If a legislative subcommittee does not meet or does not find the regulation deficient within 30 days of publication, the regulation takes effect.

The only U.S. manufacturer of sodium thiopental stopped making it in 2009 and dropped plans to resume production last year. Kentucky bought some doses from a foreign supplier, but the U.S. Drug Enforcement Administration began seizing supplies over questions of whether the states broke the law to get it. Kentucky surrendered its supply in 2011.

In the meantime, South Carolina, Oklahoma and Ohio purchased another powerful sedative, pentobarbital, to carry out executions. Ohio and Arizona have carried out one-drug executions. Other states allow it but haven't used the single drug for a lethal injection.

Shepherd's initial ruling halting all executions came as the state prepared to execute Gregory L. Wilson, 55, for the 1987 rape, kidnapping and murder of 36-year-old Debbie Pooley in Kenton County. Wilson has since won a hearing in state court on whether he is mentally disabled and ineligible for execution.

The appeals of at least five Kentucky death row inmates have run their course. They include 56-year-old Ralph Baze, awaiting execution for killing a sheriff and deputy; six-time convicted killer Robert Foley; and Wilson, all of whom remain on death row at the Kentucky State Penitentiary in Eddyville.

Kentucky last executed an inmate in 2008 and has executed three people since the reinstatement of capital punishment in 1976.

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