I first read "Drugs Without the Hot Air," David Nutt's astoundingly good book about drug policy back in 2012; in the eight years since, hardly a month has gone by without my thinking about it. Now, there's a new, updated edition, extensively revised, and it's an absolute must-read.

Nutt came to fame when he served as the UK "Drugs Czar" under the Labour Government in the late 2000s; especially when Home Secretary Jacqui Smith fired him for his refusal to lie and say that marijuana was more harmful than alcohol, despite the extensive evidence to the contrary (Smith also threatened Nutt for publishing a paper in Nature that compared the neurological harms of recreational horseback riding to harms from recreational MDMA use, a paper that concluded that if horses came in pill form we might call them "Equasy").

Since then, Nutt — an eminent psychopharmacologist researcher and practioner — has continued to campaign, research, and write about evidence-based drugs policy that takes as its central mission to reduce harm and preserve therapeutic benefits from drugs.

Like the first edition of Drugs Without the Hot Air, the new edition serves three missions:

1. First, to describe how a wide variety of drugs — benzos, cocaine, opoiods, cannabis, etc, but also alcohol, caffeine and nicotine — work in the body, in clear, nontechnical language that anyone can follow.

2. Next, to describe the harms and benefits of drugs, considered both on individual and societal levels — and also to describe what the best medical evidence tells us about maximizing those benefits and minimizing those harms.

3. Finally, to recount how governments — mainly in the UK but also in the USA and elsewhere — have responded to the evidence on drug mechanisms, harms and benefits.

Inevitably, part 3 becomes an indictment, as Nutt describes in eye-watering, frustrating, brutal detail how harmful, incoherent, self-serving and cowardly government responses to drugs have been, and how many lives they have ruined — through criminalizing harmless conduct, through treating medical problems as criminal ones, and through badly thought-through policies that caused relatively benign substances to be replaced with far more harmful ones (for example, Nutt traces the lethal rise in fentanyl partly to the successful global interdiction of opium poppies).

One important difference between the new edition and the original is visible progress on this last. In the years since Nutt was fired for refusing to lie about science, he has founded Drugscience, a research and advocacy nonprofit that has scored significant policy wins and made real therapeutic breakthroughs through hard work and rigour.

I don't think you could ask for a more sensible, clear-eyed, and useful book about drugs, from the ones your doctor prescribes to the ones your bartender serves you to the ones you can go to jail for possessing. Nutt is not just a great and principled campaigner, nor merely a talented and dedicated scientist — he's also a superb communicator.

Drugs Without the Hot Air is part of an outstanding series of technical books — mostly about climate change — that have greatly influenced my thinking. The publisher, UIT Cambridge, has several more that I recommend.

Drugs without the hot air: Making sense of legal and illegal drugs [David Nutt/UIT Cambridge]