John Rentoul: A pincer movement on No 10

The PM is caught between Kenneth Clarke, Nick Clegg, and the legal establishment on one hand, and the Tory party on the other

"I am appalled by the Supreme Court ruling," David Cameron said during Prime Minister's Questions on Wednesday. "It is about time we started to make sure that decisions are made in this parliament rather than in the courts."

It is the lot of prime ministers to chafe at the constraints of the rule of law. Tony Blair once sounded like a Ukip-voting taxi driver at one of his monthly news conferences as he railed against what lawyers (of whom he is one) would call due process: "By the time you have filled out the forms, done the statements, got them to court, three hearings, they have got defence lawyers and all the rest of it - forget it."

At other times he and his home secretaries talked of "revisiting" or even "repealing" the Chahal judgment of the European Court of Human Rights that would not allow the UK to deport a suspected terrorist. Which, needless to say, could not be done.

But that was towards the end of Blair's 10 years. Twice already in his first nine months Cameron has proclaimed his frustrating powerlessness at the dispatch box. His appalledness at the ruling on the right to appeal against being put on the sex offenders' register last week followed his confession in November that the European Court of Human Rights ruling, that some prisoners should have the vote, made him "physically ill".

What makes this more combustible is the repressed Euroscepticism of the modern Conservative Party. Yes, we all know that the European Convention on Human Rights, drafted by British lawyers, signed by the Attlee government in 1950, and incorporated into UK law by the Human Rights Act 1998, is separate from the European Union. But it is a supranational legal constraint ultimately decided on the Continent, and so it taps into the same emotional responses. Emotions that run strongly among Tory MPs, who voted by 165 to one (Peter Bottomley) against votes for criminals, with ministers abstaining.

The way in which Cameron has dealt with the constraint and the pressure typifies an emerging pattern. On votes for criminals, first he said he didn't like it but had to do it. As Kenneth Clarke, the Justice Secretary, drew up plans to give the vote to prisoners serving sentences shorter than four years, Sadiq Khan, his Labour shadow, made his move. In the first attempt by the Opposition under Ed Miliband to attack Cameron from the populist right, Khan suggested cutting this to sentences under 12 months. Miliband took fright and dropped the subject, but by then the Tory revolt was in full flood.

Cameron went with the flow. He allowed his MPs a free vote, and started to look at the options for telling the judges that he'd love to help but his MPs wouldn't let him. The Government sought legal advice on what would happen if it failed to comply with the ruling. The Times, which obtained the document last week, a top-quality, 22-carat, gold-plated leak, highlighted the bit that said the court couldn't force a country to comply: "It seems highly unlikely that the UK would face anything more than criticism at a political level if it tried to implement the judgment and failed (due to inability to get legislation through Parliament)."

The problem is that the Government still has to try, and cannot get out of this case even by the drastic step of repudiating the Convention, because that could not be retrospective. All that the Government can do about past cases is delay, but it has to pretend it is doing something about them, which is difficult when the Prime Minister has said he doesn't want to.

Nor does that stop new cases getting on to the conveyor belt. That's why last week's ruling on the sex offenders' register matters. It means that Cameron is being pushed, quite quickly, to the point where he has to decide whether to reject parts or all of the European Convention. Some Tories thought, when Cameron said the commission to draw up a new British Bill of Rights would be set up "imminently", that he had "crossed the Rubicon". I am not so sure.

Tony Blair talked about it but never did it. His home secretaries, including Jack Straw (barrister, former home secretary and co-author with David Davis of the rebel amendment on votes for criminals) looked at the same sort of legal advice as was leaked last week. Charles Clarke even legislated to opt out of a part of the Convention. Clarke drafted the law on control orders for terrorist suspects, some categories of which would have required the UK to "derogate" from the Convention, but the provision was never needed.

Blair's complaints about judges extending the Convention beyond the intentions of its drafters came to nothing. The reason being that it is impossible in practice to limit the scope of the Convention without junking it altogether (there is no provision for "derogating" from the bit on the right to vote, for example).

Yet Blair's second thoughts about the Human Rights Act, which he brought in, changes the balance of forces. A chunk of the liberal elite has changed sides. Straw mused about rewriting the Act, just as Cameron does now. Earlier this month Lord Hoffmann, the retired Law Lord who had been critical of Blair on civil liberty, renewed his attack on the European Convention and the way it has been interpreted. "The very concept of human rights is being trivialised by silly interpretations of grand ideas," he wrote. Some decisions "would have astonished those who agreed to our accession to the Convention in 1950".

Therefore, just nine months in, Cameron is between a rock and a hard place. The rock is Kenneth Clarke, Nick Clegg, most of the legal establishment, and the diplomatic embarrassment of appearing to repudiate "human rights". The hard place is the Conservative Party, including Cameron's own instincts, and public opinion, including previously supportive elite opinion typified by Blair, his home secretaries and Lord Hoffmann.

So who do you put your money on: immovable object or irresistible force?;