The US criminal justice system is a broken machine that wrongfully convicts innocent people, sentencing thousands of people to prison or to death for the crimes of others, as a new study reveals. The University of Michigan law school and Northwestern University have compiled a new National Registry of Exonerations – a database of over 2,000 prisoners exonerated between 1989 and the present day, when DNA evidence has been widely used to clear the names of innocent people convicted of rape and murder. Of these, 885 have profiles developed for the registry's website, exonerationregistry.org.

The details are shocking. Death row inmates were exonerated nine times more frequently than others convicted of murder. One-fourth of those exonerated of murder had received a death sentence, while half of those who had been wrongfully convicted of rape or murder faced death or a life behind bars. Ten of the inmates went to their grave before their names were cleared.

The leading causes of wrongful convictions include perjury, flawed eyewitness identification and prosecutorial misconduct. For those who have placed unequivocal faith in the US criminal justice system and believe that all condemned prisoners are guilty of the crime of which they were convicted, the data must make for a rude awakening.

"The most important thing we know about false convictions is that they happen and on a regular basis … Most false convictions never see the light of the day," said University of Michigan law professors Samuel Gross and Michael Shaffer, who wrote the study.

"Nobody had an inkling of the serious problem of false confessions until we had this data," said Rob Warden, executive director of the Center on Wrongful Convictions at Northwestern University.

The unveiling of the exoneration registry comes days after a groundbreaking study from Columbia law school Professor James Liebman and 12 students. Published in the Columbia Human Rights Law Review, the study describes how Texas executed an innocent man named Carlos DeLuna in 1989. DeLuna was put to death for the 1983 murder of Wanda Lopez, a young woman, at a gas station. Carlos Hernandez, who bragged about committing the murder and bore a striking resemblance to DeLuna, was named at trial by DeLuna's defence team as the actual perpetrator of the crime. But DeLuna's false conviction is merely the tip of the iceberg, as the database suggests.

Recently also, Charlie Baird, a Texas judge, was prepared to issue an order posthumously exonerating Cameron Todd Willingham, who was executed in 2004 for the 1991 arson-related deaths of his three young daughters. Based upon "overwhelming, credible and reliable evidence", Baird concluded Willingham had been wrongfully convicted; this in addition to a jailhouse witness who recanted his testimony, and scientists who challenged the evidence at trial that the fire that destroyed the Willingham home was caused by arson. Baird was blocked by a state appeals court from issuing the order before he left the bench to pursue private practice.

And again in Texas, lawyers for Kerry Max Cook, a former death row prisoner who was wrongfully convicted of a 1977 murder in East Texas, claim that the district attorney in the case withheld in his possession the murder weapon and biological evidence in the case.

In 2012, the American death penalty has reached a crossroads. Public support for executions has decreased over the years, with capital punishment critics citing its high cost, failure to deter crime, and the fact that the practice places the nation out of step with international human rights norms. Last year, the US ranked fifth in the world in executions, a member of a select club of nations that includes China, Saudi Arabia, Iraq and Iran. Further, in the US states that have repealed the death penalty in recent years – including New Mexico, New Jersey, Illinois and, most recently, Connecticut – the killing of the innocent has been cited as a pivotal factor in favor of abolition.

Meanwhile, thanks to an EU embargo on lethal injection drugs to the US, states that practice capital punishment are faced with a shortage of poison to execute prisoners. Some have resorted to purchasing unapproved drug supplies on the black market, or using different chemicals altogether. For example, Ohio has abandoned its three-drug protocol for executions in favor of a single drug called pentobarbital, a barbiturate used to euthanize animals. And Missouri has decided to execute prisoners using propofol, a surgical anesthetic implicated in Michael Jackson's death.

Apparently desperate and lacking in options to kill, these states would be better-served by joining the civilized world and devoting their efforts to end the death penalty, rather than find new methods to satisfy their bloodlust – which, as the new evidence makes abundantly clear, cannot but cause them to execute innocent citizens. According to the Death Penalty Information Center, 140 men and women have been released from death row since 1973 due to innocence. That death row inmates are exonerated much more often than other categories of prisoner – even when a person's life is at stake – should shatter anyone's faith in the presumed infallibility of the court system.

It is now transparent to the public that, at best, the application of the death penalty is rife with human error and incompetence. At worst, we know there is prosecutorial misconduct: that the courts shelter and nurture officials who are rewarded for gaming the system by career advancement, rather than determining true guilt or innocence and ensuring that justice is done.