How to prevent another mass hate killing like Christchurch

Far-right hate speech is much more common online than Islamist extremism, but governments and law enforcement have not policed it to anywhere near the same extent, say Sasha Havlicek and Zahed Amanullah.

New Zealand prime minister, Jacinda Ardern, has ordered an inquiry into whether police and intelligence services could have prevented the March 15 terrorist attack in which Brenton Tarrant killed 50 people.