>...It's after Nixon "war on drugs" stance that we begin to see harsher and harsher penalties for possession, criminalisation of usage
I don't know about other countries but the real push for harsher penalties in the US came in the 1980s after basketball star Len Bias died of cocaine overdose:
>...It became the sole focus of legislative activity for the remainder of the session on both sides of the aisle. Literally every committee, from the Committee on Agriculture to the Committee on Merchant Marine and Fisheries were somehow getting involved. Suddenly, the Len Bias case was the driving force behind every piece of legislation. Members of Congress were setting up hearings about the drug problem and every subcommittee chairman was looking to get a piece of the action
http://www.salon.com/2011/06/19/len_bias_cocaine_tragedy_sti...
>...(and this still applies here in Sweden, it's not only illegal to buy, sell or possess drugs but also to take them, if it's detected in a urine or blood test [mandatory tests if you are caught by the police] you have committed an offense)
This sounds like an internal issue in Sweden - I am not really sure how much you can blame the US for this. Certainly other countries near Sweden have more reasonable drug policies and the US doesn't try and stop that or punish the countries that I know of.
>...and then the Convention on Psychotropic Substances happened in 1971, very influenced by the US and UK stances on drugs.
The 1971 wasn't the first treaty on drugs. For example, the International Opium Convention that adopted restrictions on the opium poppy's psychoactive derivatives was in 1912.
According to wikipedia:
>...The Convention on Psychotropic Substances of 1971 is a United Nations treaty designed to control psychoactive drugs such as amphetamine-type stimulants, barbiturates, benzodiazepines, and psychedelics signed in Vienna, Austria on 21 February 1971. The Single Convention on Narcotic Drugs of 1961 did not ban the many newly-discovered psychotropics,[1] since its scope was limited to drugs with cannabis, coca, and opium-like effects.
https://en.wikipedia.org/wiki/Convention_on_Psychotropic_Sub...
>...So as much as he tried to only "look tough", Nixon has fomented one of the worst problems in modern society,
I don't think that Nixon was the first politician who tried to look tough on drugs in the US (or in other countries). Anti-drug propaganda has been produced since before "Reefer Madness" and politicians have been ranting about drugs for a long time. A difference really was that Nixon was one of the first to try to greatly expand drug treatment and reform sentencing at least in a small way:
>...the mandatory minimum sentence in a federal prison for marijuana possession was 2-10 years until Nixon slashed it to 1 year with a judicial option to waive even that sentence. No federal mandatory drug sentence would be rolled back again for 40 years (in the Obama Administration).
http://www.samefacts.com/2011/06/drug-policy/who-started-the...