THE current spat between politicians and judges over the length of sentences is just the tip of a potentially more serious dispute. The doctrines of the sovereignty of Parliament and the rule of law have come increasingly into conflict as judges challenge the executive, and the legislature, by appealing to fundamental rights.

Lord Falconer of Thoroton, the Lord Chancellor, has been left in his Corporal Jones role of saying ?Don?t panic? as he tries to ease tensions. He is correct that recent problems are less the result of judicial liberalism than of defects in existing laws and sentencing guidelines producing perverse sentences.

Yet underlying these disputes are differences over the role of the judiciary, and about whether there is a fundamental law superior to Parliament, checking its sovereignty. As Professor Vernon Bogdanor, of Oxford University, argued yesterday in the Magna Carta lecture, appeals to a basic or fundamental law are not new, even leaving aside the immortal Tony Hancock?s musing, ?Magna Carta ? did she die in vain?? The debate through the centuries has been about limiting the power of the state.

The Human Rights Act of 1998 sought to balance these rival doctrines. The sovereignty of Parliament has been preserved since the judiciary cannot strike down, or annul, a law. However, while ?declarations of incompability? by senior judges can, in theory, be ignored by ministers, they are much more than merely advisory. So the ?tenuous compromise? of the Act has required self-restraint by both judges and politicians.

But conflict between the two has occurred much earlier than Professor Bogdanor expected. There has been no consensus, particularly over the rights of asylum-seekers and suspected terrorists. Tony Blair and David Cameron (the latter a former pupil of the professor) have both talked about reviewing the operations of the Act.

Meanwhile, some law lords question whether parliamentary sovereignty will always be absolute if, for example, the government tried to alter fundamental constitutional principles, such as five-year Parliaments, the role of the courts and the rule of law. According to Lord Steyn, ?in such exceptional cases the rule of law may trump parliamentary supremacy?. Or as Lord Hope of Craighead, a Scottish law lord, said: ?The rule of law enforced by the courts is the ultimate controlling actor on which our constitution is based?.

These are not arcane issues. They have arisen directly over the Government?s reponse to the terrorist threat. That is why the imminent court ruling over the deportation of suspected foreign terrorists is so important. As Professor Bogdanor asks, who should draw the balance ? the judges or the government ? between the rights of the individual and the needs of society for protection against terrorism, crime etc? Most politicians argue that it is for elected representatives to weigh this balance. So while judges should decide individual cases, they should not seek to overturn the will of Parliament.

Some senior judges give the impression of wanting to have it both ways: of casting themselves as the guardians of the rule of law, but then being prickly and defensive when their judgments are challenged.

At present, according to Professor Bogdanor, ?the British constitution is coming to mean different things to different people?. Either Parliament will defeat the challenge of the judges, or the Human Rights Act will trump Parliament. What to him seems unlikely is that the current compromise embodied in the 1998 Act can survive over the long term. Admitting that his sympathies lie with the judges, he says that there may be ?many squalls, and indeed storms? before a new constitutional settlement emerges. That should worry all of us.