Amongst the goodies from the book are this chart , which plots dependence risk against toxicologists' ratings of physical harm for various psychoactive substances. Nutt memorably compared the "20 drugs considered in the ISCD’s 2010 report, ranked by overall harm" with their legal Class and "found a correlation of 0.04 – which means that there was effectively no relationship at all."
Also: "Francis Crick, who discovered the double helix structure of DNA with James Watson, and Kary Mullis, who invented the polymerase chain reaction (PCR), had both taken [LSD], and attributed some of their understanding and insights to it."
 http://www.amazon.com/Drugs-Without-Hot-David-Nutt/dp/190686... Drugs Without the Hot Air: Minimising the Harms of Legal and Illegal Drugs by David Nutt
It's perhaps a little UK-centric, but I found it well argued and the author is eminently credible.
Professor Nutt "Why not?"
MP "Because one's illegal."
Professor Nutt "Why is it illegal?"
MP "Because it's harmful."
Professor Nutt "Don't we need to compare harms to determine if it should be illegal?"
MP "You can't compare harms from a legal activity with an illegal one."
edit: Economist review of said book: http://www.economist.com/node/21560223
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