May 7, 2014 4:43 AM EDT

A panel of legal practitioners and policy experts have called for the implementation of a “one-drug protocol” governing capital punishment following the bungled execution of an Oklahoma inmate late last month.

The recommendation was one of 39 suggestions presented in a 165-page review of the death penalty in the U.S., which was published by the Constitution Project this week.

The broad-ranging assessment of capital-punishment procedures in the U.S. had long been in the works and shined a light on the occasionally problematic practice of using elaborate pharmaceutical cocktails to execute inmates convicted of capital murder.

The publication of the report comes a week after the botched execution of Oklahoma death-row inmate Clayton Lockett, who convulsed violently after being injected with an untested concoction of drugs from a nondisclosed source. He later died of a heart attack, 43 minutes after being injected with the unknown drugs.

“States are urged to adopt a one-drug protocol that achieves death by an overdose of a single anesthetic or barbiturate, as opposed to the three-drug method,” read the report. “The one-drug method is also preferred over the three-drug method by veterinarians for euthanizing animals because the one-drug method is more humane and less prone to error.”

The study also called on state officials to “base their choices on the latest scientific knowledge” when considering drugs to be used for executions.

States relying on pharmaceuticals to execute prisoners have had an increasingly difficult time sourcing necessary drugs as European pharmaceutical firms object to supplying their products for execution purposes. The shortage of such drugs has pushed states to increasingly reach out to undisclosed sources for lethal pharmaceuticals, drawing ire from criminal-justice experts and death-row inmates.

Following the muffled execution of Lockett last month, President Barack Obama ordered a Justice Department review into capital punishment nationwide.

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