New concerns about the effectiveness and the supply of the drugs used for lethal injections have sparked a spate of new legal actions in the U.S. and provoked lawmakers in some death penalty states to consider bringing back firing squads, electrocutions and gas chambers.
The U.S. Supreme Court banned capital punishment in 1972, deeming it unconstitutional and cruel.
Four years later, however, the Supreme Court revisited the issue and capital punishment was resurrected in the U.S., with each state having the choice as to whether or not they would allow it.
Thirty-two currently do, and, as of the end of January 2014, a total of 1,365 people have been executed in the U.S. since the death penalty was reinstated in 1976, according to the Death Penalty Information Centre in Washington, D.C.
In 1977, an Oklahoma medical examiner proposed the idea of the three-drug cocktail for lethal injections.
It soon became the norm in death penalty states, but hanging, electrocutions and gas chambers have still been in use.
Methods of execution
Lethal injection is the primary method of capital punishment in all areas where it is legal, but the following methods can still be used in certain states if the person requests it:
Electrocution: Alabama, Arkansas, Florida, Kentucky, Oklahoma, South Carolina, Tennessee and Virginia.
Gas chamber: Arizona, Missouri and Wyoming.
Hanging: Delaware, New Hampshire and Washington.
Firing squad: Oklahoma and Utah
How many times has each been used since 1976?
Lethal injection: 1,190
Gas chamber: 11
Firing squad: 3
Who was the last person to die from each method?
Electric chair: Virginia's Robert Gleason died in an electric chair in 2013. Gleason was serving life in prison for a 2007 murder, and while in jail killed two fellow inmates. He was 42.
Hanging: Billy Bailey was hanged in Delaware in 1996. He was condemned in 1980 for killing an elderly couple. He was 49. The last public execution was also by hanging. About 20,000 people showed up to watch Rainey Bethea's death in 1939 in Owensboro, Ky. He admitted to sexually assaulting and killing a 70-year-old woman.
Gas chamber: German-born Walter LaGrand died from lethal gas in Arizona in 1999. He and his brother, Karl LaGrand, stabbed a bank employee. Karl was also sentenced to death and the brothers died within a week of each other. Walter was 37. The LaGrand case was heard in the International Court of Justice, Germany vs. United States of America. Germany attempted to stop the brother's executions because the men were not informed of their right to receive assistance from the German government upon their arrest.
Firing squad: Ronnie-Lee Gardner was killed in Utah in 2010, the first person to die from firing squad in 33 years. The 49-year-old was sentenced to death in 1985 after shooting an attorney. At the time, he was facing a murder charge for shooting a bartender.
What can one get the death penalty for?
Each state has different legislation defining capital crimes, though all include murder on their list.
Other crimes that can bring about a death sentence: treason, aggravated kidnapping, drug trafficking, aircraft hijacking, placing a bomb near a bus terminal, espionage, rape of a child, aggravated assault by someone already incarcerated, and attempting, authorizing, or advising the killing of any officer, juror or witness involved in a criminal case.
Race, gender and age
As of January 2014, there are 63 women facing execution, equalling two per cent of the inmates on death row in the U.S.
Since 1976, 43 per cent of people on death row have been white, 42 per cent have been black, 13 per cent have been Hispanic, and about two per cent have been another ethnicity.
A 2001 University of North Carolina study showed that in that state, the likelihood of someone receiving the death penalty is 3.5 times higher if the victim of the crime is white.
In 2005, the Supreme Court struck down the death penalty for juveniles. Since 1976, 22 defendants have been executed for crimes they committed as youths.
George Junius Stinney is the youngest person in the U.S. to be executed under the death penalty in the 20th century. He was 14 in 1944, when he was electrocuted in South Carolina for killing two young white girls. Many people say the accusation is false, and want his name to be cleared.
Which states still allow capital punishment?
Alabama, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Idaho, Indiana, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, Wyoming.
Certain federal and military offences can also warrant the death penalty.
Since 2006, six states have abolished the death penalty, including Connecticut, Maryland and New Mexico.
But prisoners who were already on death row in Connecticut and New Mexico will still be executed. Maryland's governor has said he will examine the death row inmates in his state on a case-by-case basis after their appeals are exhausted.
Currently, there are about 3,108 people awaiting execution in the U.S. California has the most: 731.
According to the Death Penalty Information Centre, since 1973, over 140 people have been released from death row "with evidence of their innocence."
A previous version of this story stated that over 140 people have been released from death row since 1973 after "being proven innocent." Because it is not possible to determine the absolute innocence of these individuals, we have updated the story, quoting the wording used by the Death Penalty Information Centre, a non-profit organization based in Washington, D.C.Feb 06, 2014 11:59 AM ET