On Sunday, home secretary Amber Rudd argued that the “biggest driver” of rising violent crime was the illegal drugs market. The growth of so-called county lines gangs, often recruiting young children to transport drugs around the country, is fuelling our £5.3bn black market in cannabis, cocaine, ecstasy, and more.

The violence of crimes from drug gangs is spreading outwards from our cities, with an estimated 4,000 teenagers in London alone caught up in smuggling operations. Between 2014-15 and 2016-17, the share of homicides where either victim or suspect was a drug user or dealer increased from 50 per cent to 57 per cent. Competition among drug dealers has reached such a high level that some are offering loyalty cards for repeat customers.

But as politicians across the ideological spectrum discuss Band-Aid measures like tougher restrictions on buying acid and banning home deliveries of knives, the elephant in the room is our failed policy of drug prohibition.

In its recently-released Serious Violence Strategy, the Home Office inadvertently diagnoses many problems of prohibition. It correctly highlights that “grievances in illicit drug markets cannot be settled through legal channels, so participants may settle them violently. This can lead to escalation as dealers seek to portray themselves as excessively violent.”

But this is entirely avoidable: the Home Office goes on to say that “violence can be used as a way of maintaining and increasing profits within drugs markets”. In other words, the escalation happens because drugs are illegal and unregulated.

Gangs are sophisticated businesses, with strong incentives to keep their clients involved and those in their control under their thumb. Gangs in our largest cities run weapons and trafficking operations across the country. They use income from the drugs trade to finance their lifestyles, and the need to protect this feeds the firearms they trade – as seen in Liverpool where the Anfield gang jailed last year were found to be running the country’s second largest combined gun, drug and people trafficking operation with activity in rural Cheshire, Lancashire and even down to the South Coast.

The violence these gangs create is entirely the result of forcing such markets underground. Legal, regulated alcohol companies solve their disputes through competition in the marketplace, and the courts if necessary. Illegal, unregulated drug gangs often solve their disputes by the less formal methods of murdering and robbing each other.

And when police bust one gang, the resulting power vacuum can lead to heightened violence as those remaining vie for dominance. Economic evidence suggests that the introduction of medical marijuana laws (MMLs) in the USA led to a decrease in violent crime in states that border Mexico, and more wide-reaching liberalisation will have even greater effects.

But it’s not just turf wars between rival gangs that disappear under legalisation. Problem drug users are free to seek treatment without fear of arrest; campaigners are currently calling for drug consumption rooms in London, Glasgow, and elsewhere.

They are also less likely to fund their habit through theft. Washington State’s decision to legalise cannabis in November 2012 caused a reduction in thefts of between 13 per cent and 22 per cent.

Property crime is likely to plummet if other drugs were legalised and regulated according to relative harm levels: official figures show that nearly half of shoplifting, thefts, robberies and burglaries are committed by regular heroin and crack cocaine users.

Recreational users are also less likely to face violent crime. You don’t tend to get robbed at knifepoint purchasing alcohol in an off-licence, but buying cannabis in a dark alley is a different matter. Parents would no longer have to worry about the possibility that their teenage children are getting into cars with complete strangers in order to buy drugs, and any dealers who survive their market being swept away from them would face a police force with far greater resources to put them behind bars.
Last week, David Lammy MP told BBC Radio 4’s Today programme that, “The police and our country has lost control of [the] drugs market.” He’s right – but more prohibition and more police on the beat won’t solve the problem of rising violent crime. The definition of insanity is continually doing the same thing and expecting different results.

But we needn’t. The state is imposing the spillover cost of violence onto estates in our cities and onto the young people caught up in gang warfare. It has the ability to take this power away from gangs and become a world leader in harm reduction. The only way to gain control of the drugs market is to make it legal and regulated.

Daniel Pryor is head of programmes at the Adam Smith Institute.