Washington (CNN) -- The Supreme Court for the second time this week has stopped a pending execution, giving lawyers for the condemned inmates more time to file their appeals.
The justices Tuesday morning issued an order granting a stay of execution for Cleve Foster, about eight hours before his scheduled lethal injection. The Gulf War veteran was convicted along with another man of the 2002 murder of Nyanuer "Mary" Pal, a Sudanese immigrant he met at a Fort Worth bar.
The court said it needed more time to rule on the inmate's claims of prior ineffective assistance of counsel, and related claims of innocence of the murder. The state has now been given 30 days to respond to Foster's request for a rehearing of his appeals. The high court will then revisit the petition, and could then decide the execution can go forward. The court's brief order noted Justice Antonin Scalia would have denied the stay of execution.
This is the second time Foster, 47, has been granted a reprieve. His scheduled execution was stopped in January after he had already been given his last meal.
It was to be the state's first execution using a new sedative, the first in the lethal drug cocktail. A nationwide shortage of sodium thiopental forced corrections officials to recently announce they would use pentobarbital, a barbiturate that has alternately been used to put animals to sleep.
Foster's lawyers challenged that change, saying Texas foisted the new protocols so late, with little time for legal or medical review.
"I'm enormously relieved on behalf of my client and his family, and I'm glad that the Supreme Court will be looking, at least preliminarily, at the important issues we've raised," Maurie Levin, representing Foster, told CNN. "I'm very relieved Texas will not be going forward in light of all the questions and chaos using their new execution protocol."
Levin said she and her legal team were up late filing their appeals, saying the process was "very emotional." She said she has not been able to contact her client.
A Texas corrections spokeswoman said the change in chemicals was prompted by an expiration date at the end of March for the state's ready supply of sodium thiopental.
Foster's execution was to be one of seven scheduled in Texas through August. Two men had already been executed this year in the nation's busiest execution state.
The justices had also stopped Tuesday's planned execution in Arizona of Daniel Wayne Cook, issuing an order the previous evening.
He was convicted of the 1987 murder/rape/torture of two men. His lawyers had filed appeals similar to Foster's: contesting his earlier legal representation; and contesting the drugs to be used in the lethal injection, claiming they were illegally imported and may be unsafe. Cook now has several more weeks to challenge his capital punishment, and the Supreme Court may not revisit the petition perhaps until the fall.
Arizona officials had executed another inmate last week, and they had also planned on using the anesthetic pentobarbital in future executions.
Pentobarbital has become the new legal flashpoint over capital punishment. It was used in a U.S. execution for the first time in December, when it was administered as the first ingredient in a three-drug cocktail used in a lethal injection given to an Oklahoma inmate. It also has limited Food and Drug Administration approval in smaller doses for humans as a mild anesthetic and to treat some seizures. Many physicians say they no longer administer it to people for medical purposes.
Ohio last month became the first state to use the chemical as a single lethal dose. There were no reported complications and this could encourage other states to follow suit, barring any future constitutional challenges to this drug's safety and application. An execution is scheduled there next week.
In 2009, Ohio became the first state to perform an execution with a single drug, using a higher concentration of sodium thiopental. Washington is the only other state that would use a single drug.
The nation's only manufacturer of sodium thiopental had announced it was stopping production.
Many capital punishment opponents claim sodium thiopental, which renders the prisoner unconscious, can wear off too quickly, and that some prisoners would actually be awake and able to feel pain as the procedure continued.
The second drug -- pancuronium bromide -- paralyzes all muscle movement. The third drug, potassium chloride, induces cardiac arrest and death.
Some physicians warned against using pentobarbital, which is not commonly used on humans as either an anesthetic or lethal injection. Dr. David Varlotta, a board member of the American Society of Anesthesiologists, said he has not used the drug in 25 years.
"If departments of corrections are moving toward pentobarbital, they're moving away from the expertise of anesthesiologists," he said.
The European manufacturers of both pentobarbital and sodium thiopental have opposed using their products for executions in the United States.
Pentobarbital is widely available and has been used for physician-assisted suicide, including in Oregon, where the practice is legal in limited circumstances.
Thirty-four states have the death penalty. Illinois Gov. Pat Quinn in March signed legislation abolishing capital punishment for his state, following New Mexico and New Jersey in recent years.
The Texas case is Foster v. Texas (10-8317).
The Arizona case is Cook v. Arizona (10-9742).