It's a common enough question - Has the
"It should be noted at the outset that the dissent does not discuss a single case -- not one -- in which it is clear that a person was executed for a crime he did not commit. If such an event had occurred in recent years, we would not have to hunt for it; the innocent's name would be shouted from the rooftops by the abolition lobby."
Justice Antonin Scalia, Kansas v. Marsh, 2006
This is no longer the case. Now it would seem we have evidence and the rooftop we can hear it shouted from belongs to Columbia Law School in New York.
On Monday 14 May 2012, the Columbia Human Rights Law Review published "Los Tocayos Carlos: Anatomy of a Wrongful Execution". The report was led by Professor James Liebman and is based on six years of intensive research.
Carlos DeLuna was executed on 7 December 1989 for the murder of Wanda Lopez during a robbery in February 1983. He was convicted despite the complete absence of any scientific evidence linking him to the crime and despite the existence of another suspect, Carlos Hernandez, to whom he bore a physical resemblance. The Columbia law school report has also established that Hernandez spent years bragging about how he had gotten away with Lopez's murder and left his "stupid tocayo" (namesake) to take his place on death row.
The multiple flaws in the trial and the initial investigation are set out in precise detail by Prof. Liebman's team. An excellent summary can also be found in the Atlantic's article: Yes, America, We Have Executed An Innocent Man or the Guardian's article: The Wrong Carlos.
You may also be interested to read a piece from our very own Mark George QC on Sam Hallam and the Death Penalty, which discusses the implications of Sam Hallam's recent appeal victory in the context of capital punishment.