Here's a scene from The Sopranos that never got written. Tony Soprano is engrossed in one of his disputatious, sexually charged, therapy sessions with Dr Jennifer Melfi. He has just let slip something about a Mafia execution he has authorised. Suddenly the Feds burst through the door. Tony looks for an exit but it is not the mobster the police are interested in, but his shrink. She has flouted federal laws on how to talk to a client. “Dr Melfi,” they say, “last week you delivered your interpretation too close to the end of the session. We're going to read you your rights.”

It couldn't happen in America, but it could, theoretically, happen in Britain if government proposals to govern talking therapy (all forms of analysis) become law. The College of Psychoanalysts puts it this way: “Under proposed new government guidelines, most forms of psychoanalysis could become illegal.” The new law would not apply just to the NHS. Nor would it simply adjudicate complaints from disgruntled patients. The Health Professions Council, which currently regulates a smallish range of health practitioners from chiropodists to physiotherapists, will tell every Dr Melfi in the country how to do his or her job.

While some therapists do not dispute the need for some official regulation, many professional bodies are furious at these plans, including the Psychoanalytic Consortium, the Guild of Psychotherapists and the Association of Independent Psychotherapists. The Association of Psychoanalysis Users is also worried. So are NHS psychologists, who already feel in the clammy grip of the state's dead hand. Even Philip Hodson, an agony uncle who is the best-known member of the British Association for Counselling and Psychotherapy (BACP), which has campaigned for government regulation for years, says: “I don't think any form of regulation unacceptable to the cream of practising therapists is going to be workable.”

As compellingly, Lord Alderdice, the NHS psychiatrist who introduced a Private Member's Bill to set up state regulation in 2001, has warned the Government that producing a prescriptive code of skills and techniques is simply inappropriate when it comes to dealing with the unique relationship formed between Britain's 100,000 therapists and their clients.

Times Archive, 1925: Leading article: Psycho-analysis

This weapon, whether truly forged or not, is capable of inflicting terrible injuries

• Archive Topic: Sigmund Freud and the birth of Psychoanalysis

Yet a quango called Skills for Health, which is acting as gofer for a possibly reluctant Health Professions Council, has recently produced a draft of more than 450 rules that would govern therapy sessions. Some, such as the command to “identify the client's response to your use of silence”, directly contradict the teachings of the founders of analysis, Freud, Jung, Klein, Lacan and Winnicott. Another forbids interpretation too near the end of a session, a technique many counsellors rely upon. A third instructs the clinician to receive “feedback” about the helpfulness or otherwise of an interpretation. The Psychoanalytic Consortium calls it “ridiculous”. Therapy is “not about making an evaluation of service, like in a pizza restaurant”.

To put it bluntly: therapists disagree about most things, but few would argue that only one form of treatment is “right” and must be imposed. Even the word “treatment” may be a misnomer. Darian Leader, a Lacanian therapist and an influential voice at the Centre for Freudian Analysis and Research, boils the row down to a category mistake made by civil servants in the Department for Health. “The real problem is them seeing psychoanalysis as a medical intervention. They are using a medical paradigm to understand something that is not medical. Some people would much prefer to call what we do spiritual, an exploration of one's past to illuminate one's present.”

Several therapists recalled to me Freud's famous aperçu that therapy aimed to turn “hysterical misery into ordinary human unhappiness”. This is not an “outcome” likely to satisfy a bureaucrat. Nor, I suspect, would Big Brother be impressed by the efforts and modesty of a private practitioner such as Toby Ingham, a psychotherapist who works from his home in Beaconsfield, Buckinghamshire. He described to me his dealings with a typical client whom he chose to call Lewis, a divorced man in his forties who buries himself in his work to block out his feelings of loneliness. Ingham's contention is that through therapy Lewis might be able to find out more about himself and discover a more creative, and possibly more social, way of living. His feelings of loneliness would not be “banished” but explored and worked with. “The language of accountability,” he says, “has no place in emotional life. It is the language of accountancy. We can't just say, ‘Lewis, do this'. We have it in our gift to have a conversation.”

The story of how the state came to believe it should regulate these essentially private, if paid for, conversations is instructive, not least because it proves that the road to hell - or, in this case, to the 2007 Department for Heath White Paper Trust, Assurance and Safety: The Regulation of Health Professionals in the 21st Century - is paved with good intentions. It may also demonstrate the law of unintended consequences.

First, though many seem in denial, there is concern about therapists who abuse their position by, for example, starting a sexual relationship with a client. Witness, a charity that supports those abused by health and care workers, recorded 83 cases between 2005 and 2006. Jonathan Coe, its chief executive, says: “The anti-State-regulation mob seem to believe it is sufficient to have self-regulation to strike off rogue practitioners, but we know people who continue to practise after that and see people in very vulnerable states.”

Therapists speak sincerely of the seriousness with which they regard a complaint made to their governing body. Others may think that they should count themselves fortunate in being investigated by colleagues rather than outside authorities. In any case, the abused may find it hard to know which body to approach. Ingham, for instance, is registered with the BACP, the AIP (Association of Independent Psychotherapists) and UKCP (UK Council for Psychotherapy). The last is an umbrella regulator but since its foundation in 1982 it has itself splintered and is challenged by a rival outfit, the BPC (British Psychoanalytic Council). It was therefore with the best of motives that in 2001 Lord Alderdice, a Lib-Dem peer, introduced his Bill. It foundered but the Government made it clear that it wished to move in that direction. It would treat psychotherapy, for all its schisms, rivalries and acronyms, as a profession that needed to be regulated as many others had been since Thatcher began the process in the Eighties. In 1993 osteopathy became the first complementary medicine to be regulated by statute. In 2001 the Health Professions Council was created. It now governs 13 professions. Shrinkery would be the 14th - if herbalism, acupuncture and Chinese medicine don't get in first, which they might.

Within the NHS, meanwhile, there has been a parallel drive towards regulating non-drug psychiatry, at its root an admirable wish to spend public money only on medicine that works. Psychologists are now required to follow a defined procedure called step care. Sessions are counted. A patient's progress is evaluated by ticking boxes on a standardised form called (acronym alert) Core. A consultant clinical psychologist working in London says: “There is an increasingly reductionist approach to our work and on which our funding now depends.” The bureaucrats' magic bullet is cognitive behavioural therapy (CBT), which has a track record for effectively treating symptoms, such as arachnophobia, rather than causes, such as depression. Its virtues for the state are clear: it is quick, easily taught and is easily evaluated (you are cured of your fear of spiders or you are not).

It also has an economist on its side: Lord Layard, the Government's happi- ness guru who persuaded ministers that CBT would save money by taking people off incapacity benefit. We can only imagine the delight of Skills for Health, the body given the task of drawing new therapy guidelines, when it was introduced to a longer-term talking therapy. This is mentalisation based therapy, and the protesters claim that its practitioners have hijacked the consultation process and are behind the 450 new rules. Mentalisation, they say, is therapy by manual, a box-ticker's approach to psychodynamic counselling.

For those of us sceptical about Freud and his warring disciples, there is a strong urge to say they have brought this crisis upon themselves. Freud never claimed his method was a medical cure but for decades his disciples have traded on a confusion between it and science, a confusion sewn at the outset by the fact that Freud was a neurologist. When the cost-benefit analysts came to inspect the NHS's psychiatric services in the early Noughties, they could find little evidence (although analysts insist there is some) that 14 years of Freudian analysis makes you feel any better than 14 years of talking to your neighbour, friend or priest. If the state now feels it has stumbled upon a talking therapy that does cure, it is understandable that it might wish to impose it.

If the state had a super ego it might pause and consider its deeper motives. Already others are. Ingham diagnoses a state of “anxiety” in the state. Darian Leader discerns symptoms of an Orwellian control complex. Jason Wright, of the Association of Independent Psychotherapists, who ran an addiction clinic for 12 years, sees a broader tension in the culture between subjectivity and objectivity with subjectivity or personal experience losing out. In the NHS today randomised controlled trials are the gold standard for evaluating treatment. In practice, clinicians fall back on their judgment, a blend of experience, observation and opinion. Is it this that a controlling, centralised, paranoid state finds intolerable? The idea that a British Dr Melfi might ever find herself prosecuted is, one hopes, laughable. But that will not prevent the law of unintended consequence lurching into action. Some fear the new official standards will be less rigorous than those by which the profession currently regulates itself. Others, such as Wright, argue that the existence of Government guidelines will affect the quality of conversations inside the consulting room, hindering their flow. Leader imagines analysands suing their analysts for breaching the government guidelines and the legal arguments going on for years. For those sceptical about all talking “cures” there is another worry: statutory regulation will add credibility to a science that isn't a science at all, just as osteopathy, once disparaged by GPs, has blossomed since its regulation. The other possibility is this: it is the therapists who are paranoid. A spokeswoman for the proposed new regulator, the HPD, stressed its own talking was still going on and no decisions had been made. “As a regulator, our starting point is what is necessary to protect members of the public. The intention of statutory regulation is certainly not to exclude or marginalise practitioners or to promote one modality or approach to practice over another.”

At least the British Association for Counselling and Psychotherapy believes her. It thinks regulation in a modern world is essential. Ideally, it might have preferred its own rule book to get statutory backing or to be asked to help to set up a new regulator. “But,” says Philip Hodson, its chief spokesman, “we have been told that it will be regulated by the HPC and if that is the price of regulation then so be it. I understand the disquiet of therapists, but there are some who argue that there should never be regulation of talking therapists. It is as if we are some kind of super-profession, fit to be our own judge and jury.”

Yet Hodson is privately worried that the new proposals are reductive. “We can't redefine therapy as mentalisation or impose a process that seems to ignore the existence of the unconscious mind.”

Never mind that, you might say. This Government can't even regulate our banking system. Can it be in its right mind to believe it can police personal conversations freely entered into between two parties behind closed doors? Tony Soprano would surely tell this latest incarnation of the Nanny State where to go. Dr Melfi would purr something more eloquent: “Perhaps Big Brother would care to make an appointment?”