COLUMBIA, S.C. (AP) — Lawyers for four death row inmates who have run out of appeals are expected to argue to the South Carolina Supreme Court that the state’s old electric chair and new firing squad are cruel and unusual punishments.

Attorneys for the inmates also plan to argue Tuesday that a 2023 law meant to allow lethal injections to restart keeps secret too many details about the new drug and protocol used to kill prisoners.

In the balance are the death sentences of 33 inmates who are on South Carolina’s death row. While there hasn’t been a formal moratorium, the state hasn’t performed an execution in nearly 13 years after the drugs it used for lethal injection expired and companies refused to sell more to prison officials unless they could hide their identities from the public.

South Carolina says all three methods fit existing protocols. “Courts have never held the death has to be instantaneous or painless,” wrote Grayson Lambert, a lawyer for Gov. Henry McMaster’s office.

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If the Supreme Court justices allow executions to restart and any additional appeals are unsuccessful, South Carolina’s death chamber, unused since May 2011, could suddenly get quite busy.

Four inmates are suing, but four more have also run out of appeals, although two of them face a competency hearing before they could be executed, according to Justice 360, a group that describes itself as fighting for the inmates and for fairness and transparency in death penalty and other major criminal cases.

The state asked the Supreme Court to toss out a lower court ruling after a 2022 trial that the electric chair and the firing squad are cruel and unusual punishments. The justices added questions about last year’s shield law to the appeal and Tuesday’s arguments.

Circuit Judge Jocelyn Newman sided with the inmates whose experts testified prisoners would feel terrible pain whether their bodies were “cooking” by 2,000 volts of electricity in the chair, built in 1912, or if their hearts were stopped by bullets — assuming the three shooters were on target — from the yet-to-be used firing squad.

South Carolina’s current execution law requires inmates to be sent to the electric chair unless they choose a different method.

Lawmakers allowed a firing squad to be added in 2021. No legislation has been proposed in South Carolina to add nitrogen gas, which was used for the first time to kill an inmate last month in Alabama.

On the shield law, attorneys for the inmates argue South Carolina’s law is more secretive than any other state. They said prison officials should not be allowed to hide the identities of drug companies, the names of anyone helping with an execution and the exact procedure followed.

In September, prison officials announced they now have the sedative pentobarbital and changed the method of lethal injection execution from using three drugs to just one. They released few other details other than saying South Carolina’s method is similar to the protocol followed by the federal government and six other states.

The inmates argue pentobarbital, compounded and mixed, has a shelf life of about 45 days. They want to know if there is a regular supplier for the drug and what guidelines are in place to make sure the potency is right.

Too weak, and inmates may suffer without dying. Too strong, and the drug molecules can form tiny clumps that would cause intense pain when injected, according to court papers.

“No inmate in the country has ever been put to death with such little transparency about how he or she would be executed,” Justice 360 lawyer Lindsey Vann wrote.

Lawyers for the state said the inmates want the information so they can piece together who is supplying the drugs and put them under public pressure to stop.

“Each additional piece of information is a puzzle piece, and with enough of them, Respondents (or anyone else) may put them together to identify an individual or entity protected by the Shield Statute,” Lambert wrote.

South Carolina used to carry out an average of three executions a year and had more than 60 inmates on death row when the last execution was carried out in 2011. Since then, successful appeals and deaths have lowered the number to 33.

Prosecutors have sent only three new prisoners to death row in the past 13 years. Facing rising costs, the lack of lethal injection drugs and more vigorous defenses, they are choosing to accept guilty pleas and life in prison without parole.