Editor's note: Megan McCracken and Jennifer Moreno are attorneys with the Death Penalty Clinic, Lethal Injection Project, at the University of California, Berkeley School of Law. The opinions expressed in this commentary are solely those of the authors. CNN's original series "Death Row Stories" explores America's complex capital punishment system. Join the conversation about the death penalty at facebook.com/cnn or Twitter @CNNOrigSeries using #DeathRowStories.
(CNN) -- On Wednesday, July 23, the State of Arizona executed Joseph Rudolph Wood in the fourth visibly bungled execution this year. The execution began at 1:52 p.m. According to eyewitness Michael Kiefer, "Wood was unconscious by 1:57 p.m. At about 2:05, he started gasping." He continued to gasp for over 90 minutes.
Afterward, eyewitness Troy Hayden reported, "Joe Wood is dead, but it took him two hours to die. To watch a man lay there for an hour and 40 minutes gulping air, I can liken it to, if you catch a fish and throw it on the shore, the way the fish opens and closes its mouth."
Kiefer counted more than 640 gasps.
Arizona engaged in a failed experiment. Its new execution protocol called for administration of two drugs, midazolam and hydromorphone. The only other time this drug combination had been used was the prolonged and similarly disturbing Ohio execution of Dennis McGuire, who took 24 minutes to die and struggled for air for 10 to 13 minutes.
Eyewitness Alan Johnson reported that McGuire "gasped deeply. It was kind of a rattling, guttural sound. There was kind of a snorting through his nose. A couple of times, he definitely appeared to be choking."
Faced with these well-documented problems, Arizona adopted Ohio's procedure but increased the amount of each drug (from 10 milligrams to 50 milligrams for midazolam and from 40mg to 50mg for hydromorphone). The state refused to reveal, however, its process for selecting the new doses or whether it conducted due diligence to determine that its protocol would be more effective. Notwithstanding the changes Arizona made to the drug formula, Wood's execution went even worse than McGuire's.
Despite requests from Wood's lawyers, Arizona also refused to reveal the source of its drugs -- including the manufacturer, lot number and expiration date -- and the qualifications of its execution team members.
Nothing about this information would compromise the identity of those participating in executions, but it would allow the courts and the public to analyze whether the execution procedures will work as intended and bring about death in a way that meets the requirements of the Eighth Amendment.
Four men -- Michael Wilson, McGuire, Clayton Lockett and Wood -- have been subjected to bungled executions this year. Although the drugs, doses and other details of the procedures differed in each execution, the commonality between them is that the departments of corrections used experimental drug combinations and shielded crucial aspects of their practices in secrecy.
Even in the aftermath of the executions, the lack of transparency continues. While governors in both Oklahoma and Arizona have called for reviews of the problematic executions, no outside authorities have been brought in to conduct the investigations.
Internal investigations are insufficient to the task. Departments of corrections cannot be allowed to provide pat explanations that leave central questions unanswered, minimize errors and hide relevant information about what went wrong.
Instead, there must be independent investigations of each execution that goes awry and thorough, public reporting of the results. Without truly independent investigations, it will be impossible to make meaningful conclusions about what went wrong or to determine if changes can be made to ensure that the same errors do not happen again.
The botched executions in Arizona, Ohio and Oklahoma show us that when states are allowed to devise novel, untested execution protocols without judicial scrutiny or public oversight, the resulting procedures are unreliable. And when the unreliable procedures are implemented, the consequences are gruesome and horrific.
States cannot be allowed to continue carrying out death sentences without judicial review of their execution procedures. The courts must require departments of corrections to disclose key aspects of these procedures, particularly with respect to the provenance of the drugs used and the qualifications of the execution personnel.
Without this oversight, botched executions will become the new norm. No additional executions should proceed until the states act with transparency, and the courts scrutinize execution procedures to ensure that they comport with the U.S. Constitution.