The gas chamber is being officially retired in California as a method of execution—for animals

Image: Jim Urquhart/AP Images for The Humane Society of the United States
We may earn a commission from links on this page.

In 1998, California forbade shelters from euthanizing animals in gas chambers, calling the practice unnecessarily cruel. But the poorly-written law mentioned only carbon monoxide gas in publicly-funded shelters, unwittingly exempting the use of carbon dioxide.

That 18-year-old loophole effectively closed last week, when officials in Coalinga, California, retired the state’s last known animal gas chamber. A bill currently working its way through the state legislature would formally change the law.

California was one of only five states that still euthanize shelter animals via gas chamber. Only Utah, Wyoming, Missouri, and Ohio currently allow the practice.

While injected drugs can end an animal’s life painlessly in seconds, death in a gas chamber can be a torturous process lasting as long as 15 minutes. Twenty-one states have outlawed gas chambers altogether. Another 24 have no formal bans, but also no known operating gas chambers, according to the Humane Society, which is campaigning to ban them nationwide.

California has grappled with death by gas for humans as well. Of the 31 states that still employ the death penalty, California is one of five that retains the gas chamber, although California inmates get the gas chamber only if they choose it. Arizona, Missouri, Oklahoma, and Wyoming allow the use of gas should other methods be unavailable or ruled illegal.

In 1994 a federal judge in California ruled the gas chamber a cruel and unusual form of punishment, a decision subsequently upheld two years later on appeal. The US Supreme Court later vacated that ruling, but ruled in a separate 1999 case that an inmate couldn’t challenge the constitutionality of a method of execution, if he or she chose it himself. California law currently mandates that executions be carried out by lethal injection, unless the inmate chooses gas. None have.