Supported by Bernard Jenkin and some others of his fellows, Bill Cash has sent a note to all Conservative MPs dated 7th January and titled "The EU Bill: Parliament, judges and the national interest". The recipients are urged to support Cash’s proposed amendments to Clause 18 of The EU Bill.

Cash wants that clause amended so that it gives effect to what, he believes, was a pre-election promise by the leaders of his party, to re-affirm the sovereignty of our Parliament and to clip the wings of "unaccountable judges" -  our judges.

What worries him and his allies in particular is the notion that the doctrine of parliamentary sovereignty is a "common law principle" -  part of our common law. It worries them because our common law has been (and is being) made by our judges and, as Lord Stein pointed out in the Jackson case – much referred to in the Cash note - can be changed by them. Cash wants the judges "out of it", particularly because a number of them, presently very senior ones, cast doubts on the supposed immutability of the doctrine.

It is, I think, correct that the judges did not construct 'parliamentary sovereignty' and that it is not embedded in our common law. But it is most certainly not laid down anywhere as ‘holy writ’. It has a ‘dodgy’ history closely connected with the way in which the emerging political parties stole from the parliamentarians much of the power that had been wrested from our monarchy and, as a consequence, gained huge influence over the development of popular representation and our parliamentary democracy.

Oliver Cromwell did not believe in the doctrine: he was certain that the powers of Parliament were limited. He was sure, as an example, that Parliament could not indulge in self perpetuation. This little know part of our history was referred to in 1949 by that great jurist Hersch Lauterpacht when he forecast a clash between the emerging international human rights movement and believers in British parliamentary sovereignty. And that, I suspect, is what the Cash note is really all about.

In it, Cash refers to remarks of our great former law lord, Lord (Tom  - as he liked to be called) Bingham. It is true that in delivering his Jackson judgement he said "the bedrock of the British constitution is . . . the supremacy of the Crown in Parliament". It is also true that he said many other things, both in that judgement and in subsequent lectures.

In particular Tom Bingham was worried by the problem that Parliament had created for the judges when, in the Constitutional Reform Act of 2005, it asserted that ‘the rule of law’ is an existing principle of our constitution. What, he asked, were the judges to do if Parliament passed a law that was not compatible with the rule of law? Don’t let us kid ourselves that that could not happen. That is why I, for my part, agreed with and quoted two years ago the Swansea University student who said to me ‘Parliamentary supremacy is fine: parliamentary sovereignty sucks.’

Tom Bingham did not know what the answer should be but was clear that one had to be found. Not least,  this was because he believed deeply that an important component of the rule of law is the obligation of nations to honour their treaty commitments, not least in respect of fundamental human rights. Vernon Bogdanor, a former tutor of David Cameron, has said that finding the answer may be preceded by a constitutional crisis. He may turn out to be right.

I do not think that even Cash and his supporters think that the problem can be solved by saying ‘Parliament will decide what the rule of law is'. And, presumably, they do not want Parliament to recant and say that, on reflection, the rule of law is not an existing principle of our constitution.

This is not a trivial matter. Cash is challenging the Coalition and giving it a choice. Either our freedoms, our human rights, are protected by the rule of law (of which our judges must number amongst the interpreters and protectors) or those freedoms are defined and protected by a sovereign parliament which can do anything it likes.

If Parliament did what Cash and co want, we would be faced with the Bingham dilemma -  in spades. Even if this were not the case, with our representative democracy in its present state, I am clear where my preference is. I hope that Bill Cash is ignored by his Tory fellows. He is up to no good and is  wrong, dangerously wrong.