He is the man who cut his legal teeth on the infamous Oz trial, when, in the summer of 1971, three long haired participants of the permissive society appeared in the Old Bailey facing the threat of life imprisonment. The charge: conspiracy to corrupt public morals. There was the time when he protected Gay News from the wrath of Mary Whitehouse.
Those were the days in 1974 and '75 when the cases against the Birmingham Six, the Guildford Four, and Judith Ward were prepared for evidence and tried. When, as Robertson explains, the moral mind-set in courtroom and press room and police interview room was convict, convict, convict. Justice played no part.
Today Robertson has not lost any of his zeal for reform. His new mission? Incorporating the European Convention on Human Rights into UK law.
"The Human Rights Bill is the most important piece of legislation in my time."
He believes that the Bill will provide an enormously valuable bedrock set of principles which go all the way back to the Sermon on the Mount and to the life and canons of Christ.
Of all the principles in the Human Rights Bill, it is perhaps the individual's right to privacy for which Robertson has campaigned most vociferously. But does "privacy" mean that the private life of politicians remains private? Was the exposure of Robin Cook's affair in the public interest? "Of course. It was a situation where the private life could not be disentangled from the public.
"Piers Merchant's adultery was also in the public interest because he was someone standing for election on a family platform and was at the same time having an affair. For Robertson, hypocrisy in politicians will always be in the public interest. The press can never be stopped from publishing the facts that X is having an affair with Y. But, and this is where he thinks the exposure of the Piers Merchant affair went too far, certain areas are off limits.
"The grave, the toilet, the cradle, the school, the bedroom should - in my view - be generally out of bounds."
Even if great acts of hypocrisy were being committed in those spaces?
What if famous people - even Duchesses - were in a semi-private space such as by the pool in Fergie's villa in the South of France?
"Hard cases. Toes sucked on a public beach falls on one side. Toes sucked in a private bedroom - a camera secretly put in the wall - invades privacy."
"Those who argue for a privacy law cannot protect people against their own stupidity, against the company they choose to keep, that's why any law to protect privacy has to be so narrowly drawn and applied to those handful of places, and applied not to the information that `X is having an affair with Y', but to what can be published about the intimacies of the relationship."
Did Diana deserve everything she got from the press?
"It may perhaps be said that she wanted privacy when it suited her and she invited the attention, but when it wasn't to her liking she cried wolf."
He is the first to concede that the practical application of a privacy law may prove to be extremely complicated: "This is one of the interesting things that you struggle with as a lawyer.You talk in general terms and then when you come to individual cases you see grey areas. Only when these hard cases are taken to trial and tested by the courts can a sensible line can gradually emerge."
While legal reform is one way of civilising society, the winds of change can also blow from another quarter. Robertson credits the Sixties flower children, the members of the alternative society for changing the mind- set of the old Establishment, making legal reforms possible.
"Oz was provocative - it was the little boy who said the emperor had no clothes that got locked up; and the emperor did have no clothes. The real corrupters were the police and not the people who were prosecuted."
Does anyone in contemporary Britain carry the Oz mantle today?
"There has been very little in terms of the art I've seen that has been so seriously discomfiting that it has warranted any kind of crackdown - you had Damien Hirst's work at the Sensation exhibition. It doesn't strike me as being particularly sensational - I'm not bothered by the sight of a slightly dog-eared shark in a tank."
Oddly enough, it is that eager interior decorator, Lord Irvine who Robertson nominates for the position of Nineties radical revolutionary.
"He may have been a bit club-footed in his public utterances, but I just wish journalists would lift their eyes from the cost of his wallpaper and see what he's doing in respect of human rights. I think his work on the British Constitution will mark him out as a true legal strength, a legal genius.
What of Robertson himself? Is he still as anti-establishment as ever?
"No. Others describe you as that and hang these labels on you, of being radical or anti-establishment. I've never seen myself as living up to those labels."
He cannot believe in a system of censorship for works of art or literature. Again, I am surprised.
"There are crimes that are constituted by inflicting serious harm on others and there are crimes that are constituted by inflicting sexual activities on minors, and I cannot for myself readily imagine those crimes being committed in an artistically beneficial way."
What if such performance art took place in an opera? Robertson's reply is simple: "I would seriously question the sanity or stability of the director."
Should censorship apply to prevent children from viewing certain works of art, such as those of Dinos and Jake Chapman's? How does that relate with the fact that the edition of Oz that was prosecuted happened to have been the one-off Schoolkids Edition
"It was edited by them - it was their own work. I think there is all the difference in the world between children who are trying maybe to amateurishly produce something themselves, and that of the work of adults and artists who are working for adult consumption."
"The question is however, society does not restrict adults from looking at it and purchasing it but society does impose restrictions for the benefit of its children and things that we want to keep away from children - unless we assume that they are old enough to understand."
Robertson concedes the arbitrary nature of censorship laws relating to children. He admits that the real answer depends on the actual child, and that there are very advanced children of 15 who would not be affected at all by certain works of art.
"I'd be happy, as a parent, to be left to judge what influences - knowing my child best - he should be subject to. But nonetheless I am grateful to the law for at least ensuring that children are not subjected to gratuitously offensive material."
So maybe not quite as radical and daring as we thought. Here's a clue: look at what his radical chums from the Sixties, such as John Birt and Anna Wintour, are up to now: they form useful parts of the new Establishment. He laughingly quotes George Melly.
"George calls it `revolt in style'. Dissident culture is eventually picked up by the mainstream and turned into money and you end-up with boutiques called "Che Guevara". Isn't it always the secret desire of the alternative society that it wishes to get into the mainstream and to get some power for itself?
That's where Robertson is now, in the arms of power and the new Establishment.
`The Justice Game' by Geoffrey Robertson is published by Chatto and Windus, pounds 20Reuse content