March 19 (UPI) -- The U.S. Supreme Court on Monday denied a plea to review an Arizona death penalty case that questions the constitutionality of capital punishment, both locally and nationwide.
The request in Hidalgo vs. Arizona was based on an appeal of the death sentence given convicted killer Abel Hidalgo, who killed two Arizona men in 2001 and two Idaho women a year later.
Lawyers for Hidalgo argued the death penalty is unconstitutional because there are "so many aggravating circumstances that virtually every defendant convicted of first-degree murder is eligible for death."
Defense attorneys said such a broad and arbitrary sentencing could violate the Eighth Amendment prohibition against cruel and unusual punishment.
"States simply cannot provide the guidance necessary to ensure that the penalty is imposed only on the worst offenders," defense attorney Neal Katyal said. "Nor can states administer the penalty without ensnaring and putting to death the innocent."
The Supreme Court's four liberal justices acknowledged Monday that there may be constitutional issues with capital punishment, but Hidalgo's attorneys had not developed enough of a factual record for the case to be ready for review.
"The record as it has come to us is limited and largely unexamined by experts and the courts," the court's decision stated.
Lawyers obtained evidence through public records requests that showed 856 out of 866 -- 98 percent -- of first-degree murder defendants in Maricopa County, Ariz., were eligible for the death penalty based on aggravating circumstances.
Since the requested review hearing was denied, justices said they didn't have enough evidence to determine the nature of the county's 866 cases, which they said may "implicate a small number of aggravating factors."
The high court ruled in the 2015 case that the sedative midazolam, a controversial inclusion in some states' lethal injection protocol, is an acceptable drug to use in carrying out death sentences.
In their request for review, Hidalgo's attorneys cited the three-year-old dissent from Breyer and Ginsburg.