The so-called acquis communautaire is a much bigger threat to decentralisation in Europe than the single currency

There is an aspect of the European Union that is potentially more sinister than the single currency is alleged to be by its opponents but which is hardly ever discussed in English-speaking countries and not very much on the Continent either. This is the acquis communautaire.

It is significant that the term exists only in French. Attempted English translations such as "community patrimony" or "community heritage" are clumsy and unconvincing. It means, in fact, the entire body of laws, policies and practices that have evolved up to the present in the EU.

The expression made its first official appearance in the 1992 Maastricht Treaty, under which it became an explicit objective of the Union "to maintain the acquis communautaire and build on it".

One reference book notes that it "lies at the heart of the rachet process of European integration, since it commits the member states to accept all previous and future centralising measures".

The doctrine is mentioned mainly when fresh countries become members of the EU. One example was the reluctant acceptance by Denmark, Ireland and the UK of the Common Fisheries Policy, which had been agreed only two years before these countries joined. It has been in the news more recently because applicant countries are being forced to accept the whole of the acquis. This includes not only the decisions of the Council of Ministers and the Brussels Commission, but all the rulings of the European Court of Justice.

Several central European leaders whom I have met mop their brows when the topic is mentioned. For the acquis covers 80,000 pages - pages, not words - in the English edition and more in the German one. Most of them refer to that inspiring topic, the Common Agricultural Policy.

Many politicians and officials from the applicant countries have found many specific parts of it either unsuitable for their own needs or objectionable in principle. But they are reluctantly accepting it as the price of membership that they value for political reasons. This may be part of the reason why one adviser to a central European government said that negotiating with the EU reminded her of negotiating with the nomenklatura in the old Soviet Union.

One immediate question that should occur to anyone is how the acquis communautaire, which involves accepting everything that has gone before, can be compatible with the principle of subsidiarity - that decisions should always be taken at the lowest feasible level - which was introduced in the Amsterdam treaty of 1997. Some lawyers seems to think subsidiarity is applicable only to future developments. It does not therefore affect what has gone before.

In fact, however, acquis communautaire concerns existing members of the EU, and not only applicant countries. For it does tend to entrench the status quo and place an obstacle in the way of those who would like to repatriate aspects of policy, such as the Common Agricultural Policy, to the national states.

Strictly speaking, a piece of EU legislation can be repealed or amended just like a French or British or US law. But it is a much more difficult and cumbersome process at the European level. The very procedures, such as unanimity and weighted majority voting, inserted to slow down the process of integration serve also to slow down the reform of unwise enactments.

And whatever the lawyers may say, there is undoubtedly a conflict of spirit between subsidiarity and the acquis communautaire. The defenders of the acquis will say that if someone wants to join a club he or she should accept the club rules. In fact, the example shows the limitations of the club analogy. For how many clubs are there that have 80,000 pages of rules? A more convincing riposte might be that the laws of any state, when set out in full, must run to a great many pages.

The fact that the argument can be set out in these terms shows how many of the attributes of a state the EU has acquired. Not, of course, a unitary state nor even a federation. It is rather a confederation run by member nations whose representatives make decisions partly by unanimity, partly by majority vote and partly by delegation to lesser bodies.

The historical examples of confederation are not encouraging. They include the Confederation of American States, which gave way to the USA in 1788, and the 19th century German Confederation, largely ineffectual until it was replaced by a united Germany based on Prussian hegemony. About its only achievement was a writ for the arrest of the composer Richard Wagner, who had to take refuge in Switzerland.

Some of us remember the complaint of Dr Henry Kissinger, the former US secretary of state, that when he rang up to ascertain a European point of view he found there was no one at the other end. A more recent comment about the proposed European rapid reaction military force was that the whole concept was a contradiction in terms.

It is too late to bemoan the form that the EU has taken. But it is not too late to try to set out those decisions that should be taken by the central organs of the EU and those that should be left to member states. The opportunity provided by the next treaty revision conference in 2004 to resolve some of these constitutional matters should be grasped. The traditional British official attitude of assuring ministers that nothing much will happen and playing down any thought of high principle is as pathetic as it is ineffective.

A sensible aim for 2004 would be to try to transform the mismash of treaties that now make up the EU into a coherent constitution. That is by far the best way of limiting the ambitions of those who want to give the central organ more power over, for instance, taxation or labour conditions than the Washington administration has in the individual states of the US.