Drug laws should be designed to minimise damage. This might sound obvious. But the UK’s drug laws – along with those of most other countries – arguably do not have this effect. Indeed there is a strong argument that in many respects the blanket prohibition, under criminal statutes, of substances from cannabis to heroin along with the myriad synthetic substances now widely used to mimic their effects, does more harm than good.

This is not a novel point of view. Drug experts in the UK and around the world have been pointing out the flaws and inconsistencies in current policies for ages, with former Colombian president, Juan Manuel Santos, among those who have argued for a new approach focused on human rights and public health. In the UK, polls show a majority supports liberalisation of the law on cannabis, following the example of countries including Portugal. But since this shift in public attitudes has so far been ignored by the Home Office, which instead brought in a sweeping ban on so-called “legal highs” in 2016, this week’s call for reform by a cross-party trio of MPs is refreshing.

Two former ministers, Lib Dem Norman Lamb and Conservative Jonathan Djanogly, along with Labour’s David Lammy, have been to Canada to report on the legalisation of cannabis there for a short BBC documentary. The answers they have come back with are mixed. Regulation, it turns out, is no miracle cure, with a black market still thriving. But the MPs have shown it is possible to think about this subject in a nuanced way, and to learn new things.

To say that such openness to change is overdue is an understatement. Evidence of the vicious and destabilising effects of the illegal drugs business on both producer and consumer countries is not new. Drug cartels, blamed for up to 200,000 deaths in Mexico over the past decade, have now branched into the synthetic opioids that caused an American addiction epidemic. In the Philippines, President Rodrigo Duterte has overseen the killing of 5,000 people in his uniquely murderous version of the global “war on drugs”.

While the impact in the UK is less extreme, the entanglement of drug dealing with other forms of exploitation is apparent from recent “county lines” cases in which children have been manipulated by traffickers. The rate of drug deaths in Scotland has jumped to among the highest in the world. As in the US, those convicted of drugs offences and incarcerated are disproportionately black men and boys. When Michael Gove, a senior government minister, has admitted taking cocaine multiple times, such disparities leave a particularly bitter taste.

Spurred on by the confessions among their own ranks, ministers should bring calm and wise heads together at the earliest opportunity. Policing and sentencing are crucial pieces of the jigsaw. Britain should not have to wait any longer for a rational, evidence-based approach to drugs.