A 40-year-old woman in California called Leslie Whiteley has just been awarded $20m (£12.6m) in damages against two giant tobacco companies, RJ Reynolds and Philip Morris. A mother of four, she now suffers from lung cancer with secondaries, and therefore cannot have long to live. She started to smoke in 1972, at the age of 13, and continued to do so for quarter of a century.

At first sight, this might seem like a triumph for the small man (or woman) over the big wicked companies. After all, they sell a product that is, in the words of our late sovereign, James I, "lothsome to the eye, hatefull to the Nose, harmefull to the braine, dangerous to the Lungs, and in the black stinking fume thereof, neerest resembling the horrible Stigian smoke of the pit that is bottomlesse". Welcome indeed to Marlboro country. At long last, the award to Leslie Whiteley offers a ray of hope to thousands, and perhaps millions, of potential litigants in a similar predicament.

In fact, the award is deeply demeaning of the capacity of the ordinary person to regulate his own affairs and is subversive of the rule of law into the bargain. While every sympathy must of course be extended to the sufferer from this horrid disease, especially at so early an age, the fact is that she took up smoking almost certainly knowing that she ought not to have done so (packets were already marked with health warnings in those days, and knowledge about many of the dangers of smoking was already so general that I never met anyone at the time who was unaware of them). It is hardly the companies' fault if the adults responsible for her welfare failed to exercise sufficient control over her to prevent her from smoking.

But once having started, whether through the natural perversity of youth or the negligence of her adult guardians, she would quickly have become addicted to nicotine: at least, that must be the justification for considering her the helpless victim of the companies she later sued. And, having once become addicted, what could she do but continue smoking for another 25 years, until her health (presumably) forced her to give up?

But is addiction really synonymous with helplessness? Does addiction so deprive us of the ability to choose between alternative courses of action that we become helpless pawns of drug pushers, whether they be tobacco companies, publicans or street corner heroin dealers?

This is an utterly self-serving conception of addiction, and the answer to the question is clearly no. Perhaps it is conceivable that there could be an addiction so powerful that it would be unreasonable to expect anyone to overcome it: but so far no such addiction has ever come to medical knowledge. Even the plaintiff, be it remembered, gave up smoking in the end - though too late, alas.

Contrary to what is commonly supposed, addiction is not a straightforwardly physiological phenomenon. Of course, there is a physiological component to it: but it is only one component among others. Even withdrawal symptoms of opiate drugs are powerfully affected by the pre-existing state of mind of the person who is withdrawing.

Addiction is not an abject state of slavery, nor does the addicted person cease to make choices. The idea that someone who is addicted to a drug has thereby lost all control of himself is nonsense. Epidemiological studies demonstrate that many people who were once drug-addicted, and who never even came to medical attention, stop taking their drug of addiction of their own volition. Only a small minority of the thousands of heroin-addicted US soldiers, for example, continued their drug abuse on returning home from Vietnam.

Experimental work suggests that even alcoholics who are physically dependent on alcohol are able to modify their drinking, if given immediate incentives to do so. Many heavy smokers who have heart attacks never smoke another cigarette afterwards. And millions of smokers have given up without having been ill in the first place. In other words, the cultural and psychological circumstances of a person powerfully affect whether he continues to take a drug of addiction or not.

Among the psychological circumstances that affect his behaviour is the belief he holds about his own ability to control himself. If he believes - self-servingly - that he is a slave to his passion, he will not even try to control himself. And the mistaken belief that withdrawal symptoms from opiates are very severe is one of the factors that keeps a person miserably in thrall to his drug.

Thus a verdict that treats a person as having been a helpless victim of a drug (in this case nicotine) actually promotes the very evil it purports to redress - much to the delight of the lawyers, who certainly do not want people to stop smoking or the tobacco companies to go bankrupt. For no egg will ever be more golden than that laid by the goose of tobacco litigation in the United States.

The American verdict is subversive of the rule of law because the companies were engaged in a business that was, and still is, perfectly legal. Sufficient bad effects from smoking were known in 1972 to deter any sensible person from taking up the habit, if he or she paid any attention to such matters. No number of subsequent revelations about the effects of smoking has induced any government anywhere in the world to ban smoking altogether, and in most juris- dictions the government profits more from the consumption of a packet of cigarettes than does the tobacco company that manufactured them.

Why, then, is the government not sued along with the tobacco companies? Because the chances of extracting large sums of money in compensation from the government are vanishingly small and would suit no demagogic purpose.

Meanwhile, the American verdict treats addicts (and a great many of us are addicts of something or other, at least at some time in our lives) as legal minors who lack capacity to alter their behaviour. The authoritarian implications of this are frightening.