Chicago: Illinois became the 16th US state to abolish the death penalty, capping a debate over the fairness of capital punishment in a judicial system rife with wrongful convictions.

"For me, this was a difficult decision, quite literally the choice between life and death," Governor Pat Quinn said after signing the bill into law.

Quinn, who had been a supporter of the death penalty, said, “Our system of imposing the death penalty is inherently flawed and that there is no credible evidence that capital punishment deters crime.”

Illinois spurred a national debate in 1999 after a group of students at Northwestern University were able to prove that a death row inmate was, in fact, innocent.

Then-Governor George Ryan imposed a moratorium on the death penalty in 2000 after four death row inmates were exonerated.
Calling the justice system "deeply flawed," "arbitrary," and "haunted by the demon of error," Ryan commuted the sentences of 167 death row inmates to life in prison in 2003.

Since then, 15 people have been sentenced to death in Illinois, but none have been executed. Those sentences were commuted by Quinn, who took nearly two months to reach his decision.

Some 138 people sentenced to death have been released from death rows across the United States with evidence of their innocence since 1973, according to the Death Penalty Information Center.

However, support for the death penalty remains relatively high. According to a survey, around 64 per cent of Americans are in favour of the death penalty for people convicted of murder while just 29 per cent oppose it.