Lethal injection is a means of capital punishment. It gained popularity in the 20th century as a supposedly humane form of execution meant to supplant methods such as electrocution, hanging, firing squad or decapitation.

The USA was the first nation to experiment with lethal injection as a means of execution, using it first on December 7, 1982. The concept had been proposed in 1888 by J. Mount Bleyer in New York, but was not approved. It was also rejected by the British Royal Commission on Capital Punishment (1949-1953) after pressure from the British Medical Association. Texas was the first state to adopt lethal injection after the idea was revived in the US in February 1977 by Dr. Stanley Deutsch in Oklahoma. Oklahoma followed Texas's lead that same year. Since then, the majority of US states using capital punishment prefer to use lethal injection. The practice extended outside the US when it was adopted by China in 1997, Guatemala in 1998 and the Philippines in 1999. A number of other countries have adopted the method in law but not in practice.

The injection is intravenous and is usually a mix of compounds, designed to induce rapid unconsciousness followed by death through muscular paralysis of the lungs or by inducing cardiac depolarization. In the US sodium thiopental is the common agent to bring unconsciousness, with succinylcholine chloride, pancuronium bromide, or tubocurarine chloride as a paralysing drug, potassium chloride to cause cardiac arrest or one of each kind. Death usually results within five minutes, although the entire procedure can take up to 45 minutes. The individual drugs are not mixed externally as that can cause them to precipitate; they are usually injected in sequence through one or two intravenous tubes.

One curious detail about the actual administering of the lethal injection is that the recipient's arm is swabbed with isopropyl alcohol before the needle is inserted, just as any other patient's arm would be swabbed to avoid future bacterial infections. In an execution this would not appear to be a concern, but there is always the possibility of a last-minute stay of execution. Furthermore, the alcohol raises the target blood vessels and eases insertion of the needle.

The staff that inserts the needle into the arm and injects the drugs are not doctors or nurses, as performing a medical procedure to kill the "patient" would seem to violate the Hippocratic Oath, and in the United States, the code of ethics of the American Medical Association forbids doctors or nurses from taking part in lethal injection procedures.

Is lethal injection painless?

The concern has been raised that the death is not actually humane. It has been argued that the short-term anaesthetic may wear off whilst the paralysing agent continues to paralyze the prisoners and that they die an agonizing death through slow suffocation whilst fully conscious. For this reason, the use of paralysing agents for the veterinary killing of animals has been made illegal in at least one state. However, the use of these agents for killing human beings continues.

There have also been difficulties inserting the delivery needles, on occasion it has taken over thirty minutes to find a suitable vein. Certain executions have also been marked by a surprisingly violent reaction to the injected drugs. For example, when Oklahoma executed Robyn Lee Parks in 1992, Parks gasped and gagged for nearly ten minutes until his death.

External links