Greens leader Richard Di Natale’s push to legalise cannabis makes sense at so many levels, not least of which is a correlated reduction in general crime rates which is highly likely to occur if weed is no longer sold on the black market.

In those American jurisdictions that have legalised cannabis for recreational and medical purposes there has been a marked drop in property crimes and crimes of violence.

Take Washington state. It legalised cannabis in 2012. Oregon, next door, legalised in 2014. A 2017 paper by Davide Dragone for the German based IZA Institute, found that that the “legalization of recreational marijuana caused a significant reduction of rapes and thefts” in those areas of Washington that border Oregon. The decline in crime is significant.

“For rapes, the reduction is 4.2 offenses per 100,000 inhabitants, which is about 30% of the 2010-2012 rate. For thefts, the reduction is 105.6 offenses per 100,000 inhabitants, which is about 20% of the 2010-2012 rate,” the paper notes.

Late last year a landmark study published in the The Economic Journal found that since the introduction of medical cannabis laws in the US the rate of violent crime such as robberies, murders and assaults, has declined in those areas close to the Mexico border by 12.5%.

As Professor Evelina Gavrilova, the lead author of the study told The Independent the decline is what one expects when legalisation takes place. “This means that people don’t need to buy illegal marijuana anymore so drug trafficking organisations have far fewer customers,” she said.

But wait, there’s more. Work done by researchers at University of California, Irvine published in 2017 shows a drop in neighbourhood crime when medical cannabis dispensaries are located in the area. Those findings were fortified by a study published by Jeffry Brinkman and David Mok-Lamme of the Federal Reserve Bank of Philadelphia, who examined dispensaries in Denver, Colorado and concluded “adding a dispensary to a neighborhood (of 10,000 residents) decreases changes in crime by 19% relative to the average monthly crime rate in a census tract”.

The authors note their results “are consistent with theories that predict that marijuana legalization will displace illicit criminal organizations and decrease crime through changes in security behaviours”.

The great University of Chicago economist and Nobel Prize winner Gary Becker, writing with his colleague Kevin Murphy in 2013, succinctly linked the issues of drug prohibition and crime rates:

The paradox of the war on drugs is that the harder governments push the fight, the higher drug prices become to compensate for the greater risks. That leads to larger profits for traffickers who avoid being punished. This is why larger drug gangs often benefit from a tougher war on drugs, especially if the war mainly targets small-fry dealers and not the major drug gangs. Moreover, to the extent that a more aggressive war on drugs leads dealers to respond with higher levels of violence and corruption, an increase in enforcement can exacerbate the costs imposed on society.

There is not one magistrate, judge, prosecutor or defence lawyer that I have spoken to about cannabis who thinks that the current policy settings are having any impact. If only politicians would follow Richard Di Natale’s lead — and, in fairness, the Reason Party’s leader, Victorian MP Fiona Patten, has been strident and articulate on drug legalisation for many years — then we could discuss a rational cannabis policy.

One that reduces crime, raises revenue for the state and that recognises that almost everyone in Australia treats cannabis prohibition laws with the same amount of respect they treat rules against jay-walking: little or none at all.

*Greg Barns is a barrister and a spokesman for the Australian Lawyers Alliance.

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