Reacting to news of two Iowa cousins’ bodies found in the woods some 25 miles from their homes on Dec. 8, Sen. Kent Sorenson, R-Milo, has announced plans to introduce a bill in January that would reinstate the death penalty in Iowa.

Arguing that the death penalty could have stayed the girls’ killer’s hand, Sorenson noted in an interview with the Associated Press that a criminal who kidnaps or rapes “has nothing else to lose” without the death penalty in place. “They’re going to face life in prison, so they have no reason at that point to let [the victim] live.”

While Sorenson’s horror at the girls’ slayings is certainly justified, his argument about the deterrent effect of the death penalty on criminals does not bear the weight of evidence.

In a study published by the Stanford Law Review, the researchers examined the plethora of existing studies about the death penalty’s efficacy on crime reduction and determined that a clear conclusion could not be drawn.

Given the paucity of data, not to mention the narrow margins of the statistical results of the studies analyzed, the researchers wrote, “Our estimates suggest not just ‘reasonable doubt’ about whether there is any deterrent effect of the death penalty but profound uncertainty.”

This ambiguity about capital punishment’s deterrent effect in the premeditation of crimes extends into the far larger doubts regarding the proof of guilt after the crimes have been committed. In order to sentence people to death, their crimes must be proven “beyond a shadow of a doubt.” As legal history would suggest, however, this burden of proof has proven exceedingly difficult to bear.

Since 1973, 141 inmates have been sentenced to death and subsequently exonerated because of insubstantial evidence. Likewise, in the broader range of criminal convictions, 300 prisoners have been exonerated after DNA analysis began in 1989, 18 of whom were on death row.

Moreover, the criminal-justice system is subject to both human error and political self-interest in ways that render completely objective decisions impossible and the incontrovertible nature of capital punishment morally suspect. Prosecutors and governors have historically pursued convictions and used their pardoning powers in capital punishment cases with their political futures in mind.

More importantly, in a judicial system based on a jury of one’s peers, the fact that 70 percent of DNA-based exonerations have been people of color proves that a jury cannot overcome prejudice despite the guards in place against it.

Acting upon the recognition of these truths, Iowa abolished the death penalty in 1872, only to have it reinstated in 1878. In 1965, however, the Legislature voted to abolish the death penalty, and then-Gov. Harold Hughes signed the bill into law. Despite numerous attempts of reinstatement, most notably by Gov. Terry Branstad in his 1994 re-election campaign, the ban on the death penalty has stood in Iowa for almost 50 years.

As a result, Iowa joins the overwhelming majority of the industrialized, democratic world in the abolition of the death penalty. Of this group of countries, only three retain capital-punishment laws aside from the United States — Japan, Singapore, and South Korea. Most of the countries that employ the death penalty have far less democratic governments, including China, Iran, and the Congo at the top of the death penalty enforcement charts.

Regardless of the implications of this company, however — regardless even of the competing moral claims to justice or the sanctity of human life in the debate over the death penalty — the most damning argument against capital punishment across the political spectrum is the very one Sorenson has chosen to contend with. The evidence for both capital punishment’s deterrent effect and criminals’ complete guilt is not there. In a court predicated on evidence, the death penalty cannot hold.