A botched lethal injection in an Oklahoma prison recently has led to a suspension of executions in that state pending an investigation and the U.S. Supreme Court has tightened rules for screening out death row inmates for mental impairment. Support for capital punishment remains high in the United States, but opposition to the death penalty is growing.
Recent public opinion polls by Gallup and the Pew Research Center indicate support for the death penalty in the United States has fallen by around 20 percent during the past two decades. The Pew poll showed a drop of 10 percent in just the past two years in respondents who "strongly favor" capital punishment.
But the same polls show overall support for the death penalty remains strong, around 60 percent. Other polls, taken after terrorist attacks or mass shootings, show even more support for the punishment. The Angus Reid polling organization found 78 percent support for the death penalty among Americans in the immediate aftermath of the 2013 Boston bombings.
Death penalty opponents portray this as an anger-driven desire for revenge, but Dudley Sharp, an independent death penalty advocate based here in Houston, says what supporters seek is just retribution.
"Just retribution means a lawful and proportional sanction to the crime that was committed, as opposed to revenge, which neither needs lawful, or proportional or even guilt or innocence to be involved with it," said Sharp.
Opponents cite studies that show murder rates are not affected by the death penalty because most murders are not premeditated. But Dudley Sharp says the prospect of death is a deterrent.
"It is impossible to prove that the death penalty is not a deterrent for the simple reason that all prospects of a negative consequence deter some of the people. No study has ever said, nor can it, that none are deterred by the death penalty, and in fact we have 28 studies since 1999 stating that the death penalty does deter," he said.
One of the main reasons people cite for opposing the death penalty is the exoneration in recent years of around 140 people who were on death row. A statistical study by the National Academy of Sciences released last month showed that one out of every 25 people sentenced to death in the United States may be innocent.
Activist Kathy Spillman of the Witness to Innocence organization, which opposes capital punishment, says the more people learn about justice system flaws, the less comfortable they are with a state executing people.
"Even if you support the death penalty, you cannot possibly support an innocent person being sent to death as collateral damage to support a broken institution," said Spillman.
The U.S. Supreme Court recently ruled states must improve testing of inmates on death row to prevent execution of anyone with a severe mental disability. Spillman says that could save a lot of condemned people.
"I think a pretty significant percentage of our prison population in general, but on death row in particular, you would find severe mental health, mental and intellectual disabilities. That is one of the reasons they end up on death row," she said.
Several states that once had the death penalty have now either suspended its use or dropped it altogether. In the 32 states that continue to apply capital punishment, some juries have shown reluctance to convict accused murderers if they know the death penalty could be imposed.
The public has also been disturbed by a botched execution in Oklahoma in which the intravenous needle popped out of the inmate's arm as the poison was being administered. Some companies that manufacture chemicals that can be used for lethal injection are now refusing to sell them to states that carry out such executions.