Some people still maintain an unhealthily high confidence in their justice system, and tell me that it is unlikely for an innocent person to be convicted. But the facts researched by those who have actually looked into these matters tell a different story.
One such study revealed more than 400 wrongful convictions (leading to sentences of death) between 1900 and 1991. Fortunately, the vast majority of these were overturned, leaving "only" 23 certain cases of wrongful execution between those years. Some believe the real figure is likely to be much higher.
More than 70 wrongful convictions for a capital offence have occurred since 1973. 21 condemned inmates have been released since 1993. It's estimated that more than 1% of those on death row are misconvicted. In 1997, Joseph O'Dell was executed by Virginia despite the existence of DNA evidence proving his innocence: Virginia law says that new evidence found more than 21 days after conviction is inadmissible. And Texas executed Robert Drew in 1994 even though another man signed an affidavit confessing to the murder and exonerating Drew.
In recent years, there have been many cases of people escaping just in time. Roland Cruz spent 10 years on death row despite another man admitting to his crime shortly after his conviction, and Ricardo Guerra, a Mexican national, was released after 15 years on Texas's death row, after a federal judge called his prosecution outrageous. In 1989, Randall Dale Adams escaped execution by three days when the State of Texas suddenly decided he was innocent. In 1990, the same state freed Charles Lee Brandley after nine years on death row and twice coming close to execution. He escaped in the end, but that is nine years of wrongful imprisonment. The judge freeing him concluded that the colour of Brandley's skin had been the overwhelming factor in his conviction. In fact, each year since 1993, an average of 4.8 people on death row have been released after it has been decided their convictions were mistaken.
There are many reasons for these mistakes. Jurors opposed to capital punishment are not allowed to sit on death-penalty juries. Prosecutors are politically motivated and seek the death penalty in cases of weak evidence. Defence attorneys often have very limited resources. (Recently in Georgia, a conviction went ahead despite the defendant having no lawyer and repeating that he did not understand the law. His appeals were denied. Federal funding from Georgia's Resource Center which used to provide lawyers for the poor has been withdrawn.) Inflammatory pre-trial publicity is frequent. And politicians constantly attempt to shorten appeals procedures, making deaths of innocent people more likely. Congress's 1996 Anti-Terrorism and Effective Death Penalty Act replaces the standards of guilt required by Supreme Court rulings with new, less stringent tests.
One thing is certain - for as long as there is a justice system, there will be miscarriages of justice; and for as long as there is the death penalty, there will be wrongful executions, some of which will never be known about.