One thing is certain: if we do eventually get a written constitution for our country it will not start with the words "We the judges".

This remark is made only partly in jest. As Lord Bingham, our senior Law Lord, has made clear recently there is, in his view, a serious problem which we cannot wish away and must not ignore. To put it starkly, it is the incompatibility between the rule of law and the sovereignty of parliament.

At the centre of the problem is the role of the judges in relation to parliament (and the laws it makes) and to government (and the way in which it uses those laws). This is a defining issue of public power and therefore one of great concern for any democrat. The language we need to use to describe these things is often scorned as ‘abstract'. It isn't. It is describing the realities of processes that take time but are nonetheless all too real.

We are one of the very few representative democracies who do not have a written constitution. In most, if not all, countries which do the terms of the constitution incorporate the components of the rule of law as understood and accepted in the country concerned. If it is a democracy, this will reflect what can be regarded as the democratic, popular will. And in such democracies it is the constitution itself which is the highest law and binds all citizens and all the instruments of their state.

It then follows that the judges have a constitutional duty, usually when asked, to consider whether a law enacted by the legislature is consistent with the constitution. If they think there is inconsistency they must say so, give their reasons and strike the law down. The same approach applies if the judges are required to consider the way in which government uses its powers. Because the constitution incorporates the rule of law there may be issues of interpretation but not of incompatibility because the arrangement is coherent and legitimate.

Our position in the United Kingdom is different. We have no written constitution and what constitution we do have is subject to the will of parliament. If parliament wishes to change any part of what is believed to be our constitutional settlement, it may. That is what parliamentary sovereignty is: parliament can do anything it likes.

Well - can it? Has something changed? In 2005 parliament passed the Constitutional Reform Act. Section 1 of the act provides that the Act does not adversely affect "the existing constitutional principle of the rule of law".

In November 2006 Lord Bingham remarked in a public lecture (opens pdf) that parliament's affirmation of the rule of law as an existing constitutional principle has an important consequence for the judges. I have written about this recently. I have been thinking more about it since, and the more important the issue seems to me to become - it demands a much wider public debate.

In Bingham's view, judges are now "bound to construe a statute so that it did not infringe an existing constitutional principle, if it were reasonably possible to do so". This can only mean that (although he did not say so explicitly) in the view of our senior law lord, if it was not "reasonably possible to do so" the judges would have to rule - doubtless with great reluctance - that an act of parliament was unlawful.

Lord Bingham noted that parliament had left ‘the rule of law' undefined, leaving that, apparently, to the judges. He then proposed eight sub-rules that together could be said to make up the rule of law. Those proposals look "right" and relevant to the real world. But that gives teeth to Lord Bingham's "serious problem". What are the judges to say if parliament enacted, and government attempted to enforce, a measure which on any common sense, civilised basis could not be compliant with the rule of law? They could not remain silent.

Reader, have I lost you? I hope not. We live in a country without a written constitution. For us, parliament is sovereign. The judges may interpret the laws parliament has passed but they may not sit in judgement on parliament itself. This has been our tradition and our law. But now Parliament has described as a fact that the rule of law is a principle of our constitutional order. What happens if parliament then passes a law which seems to breach this principle? Why, it could be unconstitutional. Who can decide this? The judges.

Government ministers, and to some extent parliament, have become increasingly uncomfortable with some of the things the judges have said in declaring statutes and measures as incompatible with the Strasbourg Convention which has been incorporated (by parliament) in our Human Rights Act. But on this, the Act sets out that judges only have the power to make a declaration of incompatibility because, as the Blair government saw it, "To make provision... for the courts to set aside Acts of Parliament would confer on the judiciary a general power over the decisions of Parliament which under our present constitutional arrangements they do not possess, and would be likely on occasions to draw the judiciary into serious conflict with Parliament."

Nevertheless, such has been the political reaction to a number of judgements that it is now suggested that our Human Rights Act be repealed and replaced with a measure deemed to be more suitable for a country under terrorist threat. Leaving aside the fact that we would still be bound by the Strasbourg or European Convention (unless we disowned it completely which might not be compatible with remaining a member of the European Union), it is now doubtful whether such a move would have the expected affect.

There is little in the Strasbourg Convention that does not fit comfortably within what most people would see as the range of the rule of law, which the judges would, per Lord Bingham, still be obliged to use as a yardstick. Could parliament "cure" that by repealing the first section of the Constitutional Reform Act? That is where the phrase "existing constitutional principle" bites. It is one thing for parliament to have the ultimate sovereignty over law but, however much it may regret it, parliament does not have sovereignty over fact. And to talk of an "existing constitutional principle" sounds very much like an acknowledgement of fact. Parliament could hardly now announce and enact that the rule of law is not an existing constitutional principle!

The problem is compounded by the extent to which a combination of our political party system, the whip, the "payroll vote" and the ability of the Prime Minister to threaten a general election have made the House of Commons the servant of government. The distinction between the executive and the legislature has, for constitutional purposes, been largely lost and we have come perilously close to governmental or executive sovereignty.

Undoubtedly this has coloured both the views of the judges and those who disagree with them. For example, John Denham MP has said that, in effect, the judges have been in conflict with parliament and have gone further than just reining in government. Having been opposed to a written constitution he now favours one to limit judicial power and prevent their blocking of the democratic will of parliament. One wonders whether he realises that a written constitution which preserved the total sovereignty of parliament as he conceives it would be a strange document.

Some judges also have made alarming claims. One senior former judge is believed to hold the view that a disadvantage of a written constitution is that it would fetter the discretion of the judges. Others have suggested that the supremacy of parliament is a construct of judge made common law and "it is not unthinkable that circumstances could arise where the courts may have to qualify a principle established on a different hypothesis of constitutionalism." Those words were Lord Steyn's and featured in his judgement in the Parliament Act case (in which I was involved). In the same passage he referred to "a sovereign Parliament acting at the behest of a complaisant House of Commons" - a clear reference to the possible combined affect of a neutered House of Lords and a first chamber under the control of headstrong party government which has undermined traditional if often informal ‘checks and balances'.

Lord Bingham agrees with the view that the judges should not have the "final word" in our legal system. This is one reason that, without discussing the fine difference between "judge developed" and "judge made" law, he disagrees with Lord Steyn on the latent power of the judges to change the constitution. However, he believes that "our constitutional settlement has become unbalanced, and the power to restrain legislation favoured by a clear majority of the Commons much weakened, even if, exceptionally, such legislation were to infringe the rule of law."

He does not propose a solution but he has clearly warned of the possibilities if nothing is done. The admission of supremacy for universal, but effectively judge defined, "laws" by which parliament itself is, on its own admission, bound could, if the present position is allowed to drift on, put a large amount of social - almost legislative - power in the hands of the judges. Is this what we, or they, want?

Given that Lord Bingham is right, and that sitting on our hands is no solution, what should we do? I say "we" because this is "our" country and it is "our" problem. It is not in "our" interests to allow "our" judges and "our" parliament to get in each others hair. But it is in "our" interests that they are both effective and fit together in a clear constitutional context. The importance of "we" looking after "our" interests is emphasized by reading what Jack Straw said to the Lord's committee (opens pdf) on the constitution as recently as last October. He recommended that the whole committee read what Lord Bingham had said a year earlier about the importance for the judges of the Constitutional Reform Act. It is also clear from his evidence that either he did not understand the significance of the point or, more likely in my view, was not anxious to discuss it. If "our" government is not interested in looking after "us", "we" must.

It is difficult to see a sensible alternative to following the example of most of the rest of the democratic world and adopting a written constitution. Examining how South Africa, which needed a new constitution as a "peace treaty", went about securing popular commitment to an agreed text - and a constitutional structure that includes a constitutional court - would be a useful start.

Our government is talking about constitutional change and, with regard to the judges, is consulting on the system for appointing them which ensures their independence. That is, of course, important. But it would be better by far to settle what, when push comes to shove (as it may well), the judges are supposed to do. The debate over ID cards and the database state shows that new principles about the role, limits and powers of the state now need to be forged. At the same time the old principles of our system of sovereignty are shifting in quite fundamental ways. It is of great importance that these issues are intelligently debated in public and by the public.

Moderator: this article is part of an ongoing debate organised by the OurKingdom blog of openDemocracy and you can find a post specifically about it here.