Hans and Eva Rausing were gripped by a vice beyond their control After one stay in rehab (there were so many), he came to live with me for several months. He immediately relapsed; I didn't know. I thought the way he lived - the plates with rotten food under his bed, the dirt under his fingernails - was just him. The dirt was heroin. I didn't get it. Eventually - still not getting it - I gently asked him to find his own place. He stayed for several more months, but remained in his room - a second bedroom, a small room - accepting, or choosing, exile. When he left, finally, he disappeared. My column from 2009 was about the war on drugs. I was agnostic, then. There is a forgotten phone number scribbled in red at the top. Many sentences are crossed out. It ends: "It is a comforting thought that only about five per cent or so of any given population are addicts, or potential addicts, but it is not, I think, a view which is supported by facts. Some societies are notoriously more alcoholic than others, even those where genetic differences are not relevant. Cultures can be alcoholic, just as cultures can be violent, or peaceful. Decriminalisation of drugs might lead to the normalisation and legitimisation of a drug culture. I say might, because social predictions are notoriously difficult to make: we live in chaos, and even the beat of a butterfly's wing can change the course of history. Since then I have become more convinced by the arguments in favour of decriminalisation. Drugs, of course, are dangerous, but I don't think that the heavy hand of the state helps. Hans and Eva's house was raided a few years ago. Several people, seeing Hans drive erratically, had called the police. By then he must, I think, have been known to them, because what they did, in that immaculate house, was to walk up the stairs and kick in the locked door to the bedroom. Hundreds of doors, presumably, are kicked in every week up and down the country. The police must do their job, and they probably do it well, under difficult circumstances. They have, I imagine, a process for deciding when to kick in a door. But I do wonder slightly if the people who formulate the policy on drugs know what that heavy hand, the war on drugs, feels like, and looks like, and sounds like. Hans Rausing photographed in 2012 Addiction is a mystery. There is some evidence for a genetic disposition, but it's not straightforward. Genes do not map out one fate; they map out possibilities of fates. Physical addiction, also, masks the emotional illness. In fact the craving is more emotional than physical - it must be so, since the craving of a food addict or the anorexic act of deliberate starvation is, people say, as powerful as the cravings of a heroin addict. Every addiction has a particular profile; every addict has a drug of choice. But addiction to drugs, as opposed to food and alcohol, is also about small incremental steps into another culture. A transition. A conversion. Possession alone is unlikely to send you to prison if you are wealthy, because you are deemed unlikely to be dealing. And there are, I now know, psychiatrists who are willing to prescribe you large amounts of methadone or morphine as part of a supposed "rehabilitation" programme. Families look on in despair, but these addicts already live in a world where drugs are largely decriminalised. And it's not a safe place. In America, addicts are often committed to care by criminal judges. It's rare here, though it happened in the case of my brother. People often say that addicts have to want to get better before recovery can happen. But studies have shown that whether treatment is voluntary or not has little effect on outcome - addicts committed to care apparently have as good a chance of recovery as addicts choosing care. Spending time in a culture of recovery, with other recovering addicts, in a community of solidarity and responsibility, is the best treatment: every addict in the room understands that whether you are there voluntarily or not makes not the slightest bit of difference. They have all hit rock bottom, one way or another: giving up drugs, for an addict, is always an act of surrender. But it's important to remember that most drug-takers are not addicts, and that the human cost of the war on drugs globally is enormous. If addiction was more securely defined as an emotional illness, and more separated from the activity of taking drugs, it should be possible to decriminalise drugs. But at the same time it must be made easier to commit addicts at risk of dying into care. A year ago, on New Year's Day, I went to my brother's house. Eva was away, and I had heard that she was overwhelmingly worried about him, that he was not in a good state. The housekeepers let me in. They hadn't seen me for so long - I was, for reasons too sad to think about, banned from the house. The cat, a heavy white pedigree, was purring, pressing itself against their legs, watching me. How is he? I said. "Well, you know," they replied. Not good. We talked for a while, then I said I was going up. "You can't go there," they warned. "Oh, don't worry," I said. I'll just go up and knock on the door. Now I know I might have gone up in the lift to his bedroom, and reached him, but I didn't realise that then. I knocked, and called into the silence. Where was the state then, as I stood outside that broken door? Our only option of outside help at that point was to have him committed, and that, we had learnt, was almost impossible. When he was finally arrested, we heard, the police gave him a paracetamol to help him as he was brutally detoxing on the floor of the police cell. That lack of medical care, someone said, might have killed him. Where was the state then? Reading this again, I notice now that this is all hearsay. My only direct experience of the police was that same day, when I managed to reach, by telephone, one of the officers at the house. Eva had been found dead. He told me a little about it. I am grateful still for the kindness of his voice, and the quiet competence. And I am sorry, still, for what they had to see that day. I have a little wooden koala, standing on a chest in our drawing room. My parents went to Australia and came back with presents; this was one of them. My brother and I - little kids - used to give it to each other for Christmas, on alternate years. I still have it, 40 years later. When it's too painful to be reminded of him I put it away. I remember my brother, children climbing on him, laughing. I remember Hans and Eva together in their first flat, filled with hope after long hard years of addiction and recovery for both of them. How I wish that the beat of the butterfly's wing had taken them somewhere else. Out of all the tragic endings we imagined - and there were many - we never imagined this. The fee for this article was donated to the charity West London Action for Children, wlac.org.uk