On 25 January, the US state of Alabama executed Kenneth Eugene Smith. Thirty-six years on from being convicted of the ‘murder for hire’ killing of Elizabeth Sennett, the 58-year-old finally ‘answered for his horrendous crimes’, as Alabama governor Kay Ivey put it.

The execution was rightly condemned by liberals of all stripes. Activists, campaigners, members of the US Supreme Court and even the United Nations re-stated their opposition to the death penalty.

They were especially outraged by the method of Smith’s killing. Instead of being administered a lethal injection, Smith was subject to ‘nitrogen hypoxia’. This meant he was strapped to a gurney and made to breathe nitrogen through a mask apparatus, depriving him of oxygen.