Justices to Hear Arguments in Case Challenging Lethal Injections

They and the federal government argue that lawsuits challenging lethal injection are aimed at capital punishment itself. "Each wave of litigation engender[s] further delay in the execution of death sentences, even if the claims are ultimately not successful," said a brief filed by U.S. Solicitor General Paul D. Clement.

The court's review comes at a time of renewed focus on capital punishment. The number of death sentences imposed by juries fell in 2007 to the lowest level in modern times, according to the Death Penalty Information Center, and New Jersey last month became the first state in 40 years to abolish capital punishment. A few other states, including Maryland, have debated whether carrying out death sentences is too costly and time-consuming, compared with the alternative of life in prison without parole.

Polls show that Americans are still supportive of capital punishment but that they favor life imprisonment if given the option.

The court at times has seemed equally conflicted. Its frequent rulings on individual cases often result in 5 to 4 decisions either to uphold a death sentence or to send it back because of mistakes at the trial level.

The justices in recent years have eliminated the death penalty for the mentally retarded and for juveniles. They have also been more demanding about the evidence presented to juries during sentencing and about the competence of lawyers defending the accused.

Clay Crenshaw, an Alabama assistant attorney general pursuing the Siebert execution, said the average death-penalty case in his state takes 15 to 20 years because of legal reviews and an overwhelmed court system. "Now what we see in Alabama is the inmates raising their lethal-injection challenges at the end of their appeals," he said.

Supreme Court decisions in 2004 and 2006 opened the door to people seeking to challenge lethal-injection procedures. About half the inmates facing execution in the past two years have brought such challenges, and the evidence they presented has resulted in the procedure being at least temporarily halted in 12 states.

According to the petition filed by the Kentucky inmates, Ralph Baze and Thomas Bowling, resulting court decisions are a "haphazard flux ranging from requiring 'wanton infliction of pain,' 'excessive pain,' 'unnecessary pain,' 'substantial risk,' 'unnecessary risk,' 'substantial risk of wanton and unnecessary pain,' and numerous other ways of describing when a method of execution is cruel and unusual."

Baze killed two law enforcement officers who were attempting to serve a warrant in 1992. Bowling shot and killed a couple, and wounded their toddler, after crashing his car into theirs in 1990. Their lawyers said the lethal-injection procedures used in Kentucky and elsewhere pose a "significant and unnecessary risk" of pain that could be prevented by using another method.

"There's nothing speculative about whether there can be problems," said Elizabeth Semel, director of the Death Penalty Clinic at the law school at the University of California at Berkeley. But proving widespread problems is difficult, she acknowledged, because of secrecy surrounding the procedures and an inability to know whether inmates were properly anesthetized.

In Kentucky, where the only lethal-injection execution appeared to proceed without incident, a trial court said the inmates had not shown that the state's procedures exposed them to "a substantial risk of wanton and unnecessary infliction of pain." The state's supreme court agreed.

Now much about the future of lethal-injection executions across the country will be determined by how expansively the divided Supreme Court decides the case.

"This is one case where I don't want them to be too narrow," said Kent Scheidegger, a death-penalty proponent at the Criminal Justice Legal Foundation. He filed a brief urging the court not to decide the case "in a way that creates a moving target for a permanent new round of litigation."