Prohibition of certain substances for certain people will never succeed

One only has to look at what happened in the US after they tried to ban the sale of alcohol.  Increased crime, deaths and corruption.  The reason for that was of course an increases in profits for those willing to break the law and protect themselves violently.  Also remember that the possession and home production for own use of alcohol was never a  crime!

Failing to learn from that, most countries introduces bans on not only the commercial production and supply of certain substances but also in many cases the possession even in small amounts.  Interesting that the cultivation of hemp even with very very low amounts of psychoactive compounds such as THC was also banned - in the UK it is still an offense to grow even one hemp plant at home - suggesting that the prohibition was not only an illogical attempt to stop people taking certain psychoactive substances but was also based on other motives.

Talking first about hemp: the ban certainly enabled large-scale investors in some industries to make greater profits through the production of synthetic and other alternatives.  Hemp had been used for many hundreds of years for the production of many essentials from paper to clothing, sails to ropes, artists materials to foodstuffs, building materials to fuels, and medicine.  These were replaced by the likes of wood-pulp papers, cotton and nylon, polyurethane and plastics, unhealthy fast foods, fossil and nuclear fuels, and pharmaceutical drugs.  None of the natural hemp products were in themselves dangerous and most were environmentally friendly in their production and destruction.  Also most could be handled locally.  None of those natural products could be used to "get high".

Now let's look at the potential risks from consumption of substances ("recreational use") where possession is banned, compared with other substances where possession by adults is allowed.

Some years ago the American Medical Association produced a chart comparing the potential for addition and toxicity of various substances deemed "legal" or "illegal".  Note here that it is the production, possession, supply that comes under prohibition law, that is the human involvement, not the substances themselves that are listed in the legislation.  Note also that some people are licensed to possess, supply or produce those substances that is banned for most of us - such as scientists conduction research, police, forensic scientists and court officials or other such as teachers in the course of their duty, employment or occupations.

This was how the AMA compared the substances 

Tobacco alongside heroin, highly addictive, highly toxic.

Alcohol alongside cocaine, quite addictive and quite toxic 

Caffeine alongside amphetamines, potentially addictive, can be toxic

Ecstasy - low lever of potential for addiction or lethal overdose

LSD - very low potential for addiction and non-toxic

Cannabis - no potential for physical addition and non-toxic.

NOTE: 

in consideration of addiction, they looked at problems such as withdrawal symptoms;  This has little to do with an individual's desire to repeat a pleasant experience and did not take into account any increases in likelihood of addition due to genetic predisposition or environmental factors such as social connections.

in consideration of toxicity, they looked at the number of "normal does" required to be taken at once likely to cause death.

Now let's  look a the social costs of prohibition, billions of pounds of taxpayers money spent annually; criminalisation of often otherwise law-abiding citizens; alienation of youth, health problems due to uncertain strength and purity; availability to young people (often at the schools and colleges and at home from older siblings, as well as unscrupulous profiteering street dealers); financing of criminal gangs and maybe even terrorists; boosting money-raising crimes such as burglary, theft, muggings, shop-lifting, small-scale dealing, cutting the drugs to boost profits and prostitution.

If those substances were sold through controllable outlets such as cannabis cafes ("Coffeeshops" such as in Holland), Private Member Cannabis Clubs (such as in Spain)  or Pharmacies and Off-Licenses, where quality control and dosage could be measured and sales limited to adults, although it could reduce the price of some drugs it would bring a decrease in fund-raising crime, decrease in problematic use (more noticeable and more likely that the user would consult a  doctor without fear of arrest), decrease in the number of deaths through overdose (the strengths and dosage could be controlled), increase in revenue through taxation, decreases in costs of enforcement, court cases and imprisonment, overall better health and safety at point of sale, dis-empowerment of drug gangs, improvement in social environment and less alienation of users of some drugs compared with users of other drugs.  

After all, few people, in the UK at least, object to anyone drinking moderately at home or down the pub, so long as they do no harm to others, so why should anyone object to anyone smoking a few joints of hash pipes or even taking other substances in the same situations?

My conclusion, for many years now, is that prohibition has little to do with protecting people from harm, and a lot more about controlling people's choices and money!

Please let me know in the comments whether or not you agree.