Most of the spate of miscarriages of criminal justice that have occurred during my lifetime have been the consequence of police corruption and judicial naivety; the police in giving false evidence to secure convictions against those they have deluded themselves into thinking are guilty and the judiciary in invariably accepting their word in preference to those of innocent defendants.

One of the worst examples of this were the various injustices suffered by the Birmingham Six. Four of the Six had made "confessions" that they claimed with good reason had been beaten out of them by police brutality. This the police denied and at their trial Mr Justice Bridge supported them, describing the Six's allegations as bizarre and grotesque and praising the police who had lied in their teeth as being honest and straightforward witnesses.

Next the Six applied for legal aid to sue the police for injuries inflicted while in police custody. When this reached the Master of the Rolls, Lord Denning, he struck it out on the depraved ground that if it were proved that the confessions had been obtained by violence and threats, the Six might have to be pardoned; and this was such an appalling vista that every sensible person in the land would say it would not be right for the action to proceed.

Next the Lord Chief Justice, Lord Lane, dismissed their 1988 appeal, despite impressive new eye-witness evidence that the Six had suffered violence and abuse in police custody. To this he turned a blind eye, saying in his judgment: "As has happened before in references by the Home Secretary to this court, the longer the hearing has gone on, the more convinced the court has become that the verdict of the jury was correct."

It was the same with Mr Justice Donaldson at the trial of Vincent Maguire, of the Maguire Seven, who had also complained that the police had beaten him up. "You have seen the police officers," he told the jury, "and they denied using any violence at all." Well, they would, wouldn't they? And then in Edinburgh we saw the absurd Lord Robertson, who despite Patrick Meehan having been granted a free pardon for his wrongful conviction of the Ayr murder as a result of police fabrication of evidence (for which he had already served seven years), manage to persuade a jury to acquit Ian Waddell, who had both committed it and admitted to it, in his dotty belief that Meehan was guilty all along.

Meehan was in court to hear Robertson's charge to the jury, which so enraged him that he stormed out of the building shouting that his free pardon wasn't worth the paper it was written on while I, also there, had a strong desire to say to Robertson, "This trial has been a farce, my lord, and you are the chief clown", but wisely or perhaps cravenly refrained, thus sparing myself perhaps a longish spell in Saughton jail for contempt of court.

Further confessions, brought about by police violence or threats of violence once had a great run of successes, the police knowing that no jury would be persuaded to believe that any defendant, whatever the circumstances, would ever admit to murder unless he was guilty. Thanks to the Police and Criminal Evidence Act and recommendations of the Runciman Commission they are now out of fashion but they did immense damage; in addition to 16 years of imprisonment for the Birmingham Six and Guildford Four, the execution of Timothy Evans, the incarceration in a mental home for seven years of the perfectly sane Iain Hay Gordon and 16 years in prison for the innocent George Long for no other reason that he never ceased from asserting his innocence (which proved, according to a Mrs Harris at the Home Office, that he had refused to come to terms with his guilt).

So what reforms do we need? First and because most police fabrication occurs in the early stages of investigations, the appointment of a QC or other senior legal figure, analogous to the juge d'instruction in France, to direct and supervise all police inquiries; and in this I have the support of Michael Mansfield, QC, that most doughty and persistent of defence advocates.

A more radical reform for which I have been campaigning for 40 years would be the abandonment of the absurd adversary system of justice which we share with the United States, Canada and Australia, in all of which miscarriages of justice occur on a scale unknown in countries that practice the inquisitorial and other systems. Nor is it in the least effective, the two highest courts in France, the Cours d'Assise and Tribunal Correctionel having conviction rates of between 90 and 95 per cent, while contested pleas cases in the Crown Courts here can manage only a paltry 56 per cent.

Our system also leads to the acquittal of the guilty, permitting skilful advocates to persuade juries not to convict defendants who richly merit it, like Norman Birkett, who saw Tony Mancini walk free in the Brighton trunk murder case (though years later he admitted to it), and the late Nicholas Fairbairn, QC, in Scotland who told me of three villains he was defending and knew were guilty gain acquittal.

Are we so wedded to a system that fails us at every turn that we cannot see and welcome the need for change?

The author’s book, Thirty-Six Murders & Two Immoral Earnings, is published by Profile Books (reviewed below)

Ludovic Kennedy has a strong claim to be the founding father of all the recent "miscarriage of justice" investigations. His book Ten Rillington Place - which identified Reginald Christie, the war-time special constable, and not the already hanged Timothy Evans, as being the true murderer residing at that once-famous address in London’s Notting Hill - was first published in 1961. (It took another five years for Evans to be granted a posthumous free pardon.)

Since then, Kennedy, in whatever free time was left over from being a successful television presenter, has certainly kept at it. He went on to write five further books that questioned judicial decisions of one sort or another, of which the best is perhaps his assault on the whole conduct of the Stephen Ward case, which was the Establishment's revenge for the Profumo affair of 1963.

In a sense, Thirty-Six Murders & Two Immoral Earnings, published in its author’s 83rd year, distils all the lessons that Kennedy has learnt from this side of his experience. But there is nothing elegiac about it. Conceivably because of his top-drawer background - the young Kennedy was at Eton and Christ Church - there is, even in his old age, a raffish air of aristocratic truculence about his writing. Thus one home secretary is dismissed as a "prize ass", another as "a rather flabby individual", while a former lord chief justice of England is roundly condemned as "a bully and a sexual deviant".

Paradoxically, though, the truth about Kennedy is that he is an intensely serious individual. Fairly early on (he attributes his initial fascination with the law to reading a series of volumes entitled Notable British Trials in his grandfather's library in Edinburgh) he appears to have convinced himself that the Achilles heel of our legal system lies in its foundation on the adversarial principle ("an invitation to corruption", as he breezily brands it). If this book has a subtext, it is how much better off we would all be if only the authorities could be brought to move towards the inquisitorial system as practised in France. Under this arrangement, in serious criminal cases all preliminary inquiries are presided over by an examining magistrate.

My own view is that, while Kennedy's diagnosis cannot be faulted (our police, as he demonstrates, do fabricate evidence, and judges almost automatically believe them and instruct juries accordingly), his remedy is more questionable. He is candid enough to admit that, in his contention that the French system is infinitely preferable to ours, he has failed to carry even his natural allies along with him.

Gareth Pierce, the solicitor for the Guildford Four and the Birmingham Six to whom the book is dedicated, disagrees with him - and so does the leading radical QC, Michael Mansfield. They believe - as, I suspect, most lawyers are bound to do - that there can be no substitute for a rigorous cross-examination, whether of the accuser or the accused. Any modification of current practice (through having already established an agreed version of events) would, according to them, risk throwing out the baby with the bath water.

Yet, even if this book fails to make the case for its central reform, it supplies enough evidence to forestall any possible resort to complacency. Our contemporary judiciary, it has to be said, comes out particularly badly, and the author is fully justified in preserving the more fatuous observations of its members in a kind of rogues’ gallery complete with photographs in the centre of the book. It is hard to know who comes out worst - although it may be that it is the one-time Lord Chief Justice, Lord Lane, who, on hearing the original appeal of the Birmingham Six in 1988, even went so far as to rebuke the home secretary for wasting the court's time in referring the appeal to it at all. As a consequence, the Birmingham Six were required to endure another three years' imprisonment before having their convictions quashed in 1991. As for Lord Lane, he retired full of years and honour that very same year.

The strength of the author's position is that, by conditioning and background, he has always belonged far more to the world of Lord Lane (he actually owns up to having played golf with him) than to that of the normal prison population. It is, no doubt, unfair but - as with the "blood" at a public school who suddenly announces that he is bored with sport and is turning his back on it - a special form of integrity will always be thought to belong to those who renounce the world of which they are natural members in order to take on injustice and support the underdog. That is what Kennedy has done virtually all his life and this unusual book is a fitting testament to what has been an exceptional achievement.

Thirty-Six Murders & Two Immoral Earnings is available at a discount (ca. 25%) at the Sunday Times Books Direct price of £13.59 plus £1.95 p&p on 0870 165 8585