Maastricht is a Dutch city in the province of Limburg with very close borders to Germany and Belgium. Famous for the Treaty of 1992 which created the Euro, the Commission, the European Parliament and the European Court of Justice it seems that at a local, political level the folly has continued.

The local Mayor, Onno Hoes, has banned foreigners from smoking cannabis in the “coffee shops.” Hoes is a member of Volkspartij voor Vrijheid en Democratie, (VVD) -- in English, the People's Party for Freedom and Democracy -- a supposedly liberal, if not classical liberal party. And it is strange to see someone from such a party turning all prohibitionist. It also seems strange that the Dutch Ministry of Justice’s policy of "gedoogbeleid" or "tolerance" has evaporated like a smoke ring in a force 10 gale.

Cannabis liberalisation dates back to 1976. From then on the situation in the Netherlands has been that small quantities of up to 5 grams of cannabis and possession of 5 plants is decriminalised, but not legalised. Due to the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances of 1988 they are not allowed to legalise its consumption. People may wish to ask why governments sign up for handcuffs like this.

Maastricht’s policy is a laboratory. In May 2011, the Dutch government announced the phasing out of cannabis tourism, starting with the southern provinces of Limburg, Noord Brabant and Zeeland around the end of 2011, and then rolling the model out to the other provinces from January 2013. Some places like Eindhoven and some in the South Holland province have unilaterally passed their own legislation to contain and eliminate the tourism. The reasons given for the clampdown are that the Netherlands is a major centre and distribution point for class A drugs for Europe. (I am sure it has not escaped your attention that Rotterdam is the largest European port in terms of size and facilities.)

But how this ties in with cannabis decriminalisation is a mystery as any large scale dealer would get a lengthy jail sentence anyway. The Dutch Health and Justice Ministries were quoted on the 28th May as saying: "In order to tackle the nuisance and criminality associated with coffee shops and drug trafficking, the open-door policy of coffee shops will end."

The Dutch also raised the age of consumption in coffee shops from 16 to 18 and have added that joints with more than 15 percent Tetrahydrocannabinol (THC), will be treated as hard drugs. (THC is the psychoactive chemical constituent.)

The Netherlands is distinctly mid table when it comes to consumption levels. Average use in the developed world is 5.8 percent of the population. The Netherlands is 5.24 percent. New Zealand is the biggest consumer with 22.3 percent, Australia is at 17.93 percent, the USA 12.3 percent and the UK 9 percent. Also what is striking about consumption in the Netherlands is the decline in prevalence from 1997 to 2007 in the 12-18 year old group from 11 percent to 8 percent, with the number of coffee shops declining from 1,200 to 700.

As cannabis has become socially acceptable the curiosity and "cool" image may have lost its shine. Certainly, the academic papers seem to confirm that decriminalization or legalisation do not increase usage.

Here are a couple of sample comments:

National Academy of Sciences, Institute of Medicine, 1999. Marijuana and Medicine: Assessing the Science Base: "In sum, there is little evidence that decriminalization of marijuana use necessarily leads to a substantial increase in marijuana use."

L. Atkinson and D. McDonald. 1995: "The evidence is accumulating ... that liberalization does not increase cannabis use [and] that the total prohibition approach is costly [and] ineffective as a general deterrent."

So back in neo-prohibition Maastricht, what have been the consequences? Firstly the Big Brother "Weed Pass" registration scheme of Dutch cannabis users has failed, as people were not prepared to go the local council to register. The Maastricht mayor’s spokesman Gertjan Bos made this rather extraordinary statement: "The weed pass has been a success as 1.5 million people who used to come from abroad are not coming anymore". The drug tourists spend €119 million a year on local services.

The worst consequence of the legislation is the return of the drug dealer. “Drug dealers, some of them children and many of them from Eastern Europe and North Africa, now fight for control of the 120,000-population city. Eight of 17 local authorities that took part in a survey said they had witnessed an increase in drug-related problems since the weed pass came into force," the Limburger newspaper reported.

"Everything we predicted has come true," says Marc Josemans, head of the association of Maastricht coffee shop owners. "Some of the dealers on the street now are as young as 14, some are as old as 65. They are making good profits". Maastricht has become a "ghost town" since May, says Josemans. "I will admit there are a lot more parking spaces available, but there have been a lot of negative side effects. There is no tourism anymore."

The other effect is the need for extra police to enforce the law. Declining revenues and greater city spending: what a mess! I assume that violence will follow.

So, another prohibition is having far worse effects than the original intention. We can only hope that the Maastricht policies will be reviewed and more sensible policies adopted. However, when did you last hear a politician admitting they got it wrong?

David Atherton is Chairman of Freedom2Choose, which seeks to protect the informed choices of consenting adults on the issues of smoking. Follow him on Twitter: @DaveAtherton20