How a Michael Portillo BBC film inspired a US push for nitrogen-gas executions

But the idea to execute inmates in the US with nitrogen was actually set in motion by a rebellious and ultra-conservative lawmaker in Oklahoma, and surprisingly involves a former British Conservative MP turned television personality, Michael Portillo.

Nitrogen executions were first legislated in 2015 by Oklahoma, a US state boasts the highest execution rate per capita and a long history of death penalty innovation, having also been the first to introduce the lethal injection in 1977.

The story of its most recent innovation in execution methods involves a documentary hosted by Portillo. After a career in British politics, where he was once seen as a darling of the Conservative right, Portillo reinvented himself as a television presenter. He later became famous for shows on the BBC such as Great British Railway Journeys.

The bill had been a while in the making. By 2014, states across the country were struggling to enforce capital punishment. Anti-death penalty advocates had successfully lobbied drug companies to stop supplying them with lethal injection drugs and many states were forced to improvise. Some attempted to get their drugs via illegal backchannels while others sought out substitute compounds, but both contributed to a string of botched and messy executions.

Months later, Christian was back with another plan. He had gathered more than a dozen or so Oklahoma legislators and public officials for a judiciary committee meeting at the Oklahoma capitol to make the case for something new.

Christian was part of a highly conservative rebel faction of Republicans in Oklahoma who were further to the right than the mainstream Republicans, according to Virgin. One of his friends in that group was Senator Randy Terrill, who in 2013 was sentenced to a year in prison for bribing a Democratic candidate to withdraw from a Senate election so that Christian could have her otherwise unwinnable seat. Their mutual friend Copeland testified in support of Terrill during his trial.