Three inmates whose lives were temporarily spared amid a flurry of executions last year are heading back to court, hoping to show that Arkansas officials would violate the rights of mentally ill death row prisoners if they end the men's lives.

Separate arguments are scheduled Thursday in the Arkansas Supreme Court for Bruce Ward and Don Davis, who came within hours of being put to death last April in what had been set as the first in a series of four double executions. Documents are also due next month in the case of Jack Greene, who had been scheduled to die last November.

Arkansas justices called off Ward's and Davis' executions as the U.S. Supreme Court looked into whether criminal defendants are entitled to independent mental health experts. They stopped Greene's to consider whether Arkansas' prison director is an adequate judge of the inmate's mental health. Ward makes a similar claim in another case.

It's possible, but unlikely, that Arkansas could execute anyone before its current full batch of lethal injection drugs expires March 1. Seventy-five vials of the muscle relaxant vecuronium bromide must be tossed out after March 1; the state uses five per execution.

Gov. Asa Hutchinson's office said it wouldn't speculate on how quickly he might set an execution date if the men lose their appeals. The attorney general's office said only that it would give the governor the appropriate notice if the men's status changes.

Arkansas typically gives inmates seven to eight weeks' notice before an execution. March 1 is five weeks away.

Prison officials have not said whether they have a supplier standing by to replace its current stock of lethal injection drugs. Arkansas' potassium chloride supply expires Aug. 31 and its midazolam is good through Jan. 31, 2019.

Midazolam sedates inmates, vecuronium bromide stops their lungs and potassium chloride stops their hearts.

Arkansas executed four prisoners in an eight-day period last spring, rushing to put the men to death before their existing supply of midazolam expired April 30. They had scheduled eight executions in an 11-day period, but Ward and Davis received stays, one inmate was given more time to raise a claim of innocence and another won clemency.

Davis is closest to exhausting his appeals. Last April, public defenders argued he received inadequate assistance on his mental health claims. Arkansas justices stopped his execution because, at the time, the U.S. Supreme Court was considering a similar case from Alabama's death row. The nation's highest court ultimately ordered a new examination into whether the Alabama inmate, James McWilliams, was substantially harmed by the trial court's error.

Ward raises the same issue as Davis and in a separate case argues the director of the Arkansas Department of Correction is not qualified to assess whether he is mentally competent to understand his execution. His lawyers contend the decision would best be left to medical experts because Wendy Kelley's boss, Hutchinson, sets execution dates and her dual roles as both the executioner and the "arbiter of sanity" present a conflict of interest.

Lawyers for the state said Kelley is a "neutral state officer" who merely carries out sentences imposed by the courts.

Greene, who appeared before the state Parole Board last year with rolled-up tissues stuck in his ears, also argues that Kelley shouldn't assess his mental status.

Defense lawyers said Ward has a lifelong history of severe mental illness, including schizophrenia, and Davis has an IQ score indicating an intellectual disability.