Execution by lethal injection under renewed scrutiny

Most US states that permit lethal-injection executions prevent veterinarians from using the same method to put animals down, according to a new study.

One of the three drugs injected into condemned prisoners, the one that causes paralysis, has been banned from use in animals by at least 42 states, said the study's author, Ty Alper, a death penalty opponent and associate director of the Death Penalty Clinic at the University of California-Berkeley School of Law.

The states include the five leaders in lethal injections – Texas, Oklahoma, Virginia, Missouri and North Carolina – and account for 907 of the 929 executions by that method since 1982.

Lethal injection has been on hold while the Supreme Court considers a challenge to it in a case from Kentucky, which is among the roughly three dozen states that administer three drugs in succession to knock out, paralyse and kill prisoners. The major criticism of this is that if the executioner administers too little anaesthetic, the inmate could suffer excruciating pain from the other two drugs. This may go undetected because the paralysing drug would prevent any change in the dying prisoner's expression.

In Kentucky, two death-row inmates argue that a large dose of a barbiturate, the most common way of putting down animals, is a less painful way to carry out executions. The state prohibits using a paralytic in animal killings.

Federal judges in Missouri, California and Tennessee have ruled that the way lethal injections are carried out in those states is unconstitutional, mainly because of the risk of severe pain.

Yet states have refused to approve injection of a single drug, in part from fear that this might precipitate a new round of lawsuits to stop executions.