A cynic might be tempted to say that when politicians run out of ideas, they turn to making or changing the constitution. Take the European Union. Its last big project was the single market as conceived by Jacques Delors, the European Commission's then-President. That project has still not been completed, but the missing bits are a continuing process, not a new idea.

Since then, the EU has tried a little of this and a little of that: a little common economic policy around the introduction of the Euro, a little common foreign policy around the Iraq war. None of it has been very successful. Indeed, none of it has an advocate of the stature of Delors.

So the EU turned to constitution making. It set up a Convention, which produced a draft treaty, and soon an Intergovernmental Conference will try to take the project to a conclusion.

Chancellor Gerhard Schröder of Germany liked the idea so much that he is now thinking of setting up his own Convention to review Germany's constitutional arrangements. His target-agreed with the other main parties-is the precarious relationship between Federal authority (notably the power of the purse) and that of the Länder and local governments. Perhaps the German Chancellor hopes that in the shadows of such an all-party Convention he can quietly slip through "reforms" that are, for the most part, really cuts in public expenditure for social services.

The case of Prime Minister Tony Blair of the UK is even more extreme. The inventor of New Labour would like to be remembered as the man who squared the circle of sustainable economic growth and a reformed welfare state, the man who reconciled wealth creation and social cohesion. But the British economy is in a precarious state, and public services remain a mess.

What has changed under New Labour's rule is the British constitution. Scotland has a parliament, Wales an assembly. English regions may soon follow. London and other cities have directly elected mayors. Ancient institutions, notably the House of Lords, have been "modernized." The judicial system has seen root and branch change. In fact, Blair is reportedly not very interested in these changes, but it is they-not some beacon of British prosperity and social justice-that are his lasting legacy.

Other European leaders could be added to the list, not least Prime Minister Berlusconi of Italy. In all these cases, the cynic would be half-right. Constitutional change is for political leaders a welcome distraction from the much more change-resistant issues of social policy. But there are at least two exceptions to this suspicion.

One is the establishment of democracy and the rule of law in countries that have recently emerged from dictatorship. The process requires constitution making of an often complex and painful kind. The most recent example is Turkey, where a courageous prime minister has confirmed the secular (rather than Islamist) rule of law, sought to modernize the economy, and has kept the military out of the Cabinet.

Turkey wants desperately to be accepted into the EU, whose "Copenhagen criteria," approved in 1993, define what may be called the constitutional prerequisites of membership. The accession countries of East Central Europe all fulfilled the criteria; Turkey is now following their example.

The other serious issue of a constitutional nature is that of levels of government. In a globalized world environment, the question of who is responsible for what has become as opaque-if not unanswerable-as it is urgent. This is all the more true in view of the fact that the migration of decisions to an ill-defined global space is being accompanied by a widespread demand for more direct forms of democracy that can bring decisions closer to people, regions, and local communities.

There are as yet no "Copenhagen criteria" to guide constitution-makers here. Britain is a good example of the confusions that attend mere pragmatism. Scotland may have a new (and expensive) government, but what about the English regions? Are the East Midlands really an appropriate unit of self-government?

In Germany the issue is the distribution of tax revenue. Central government can easily starve the regions and local communities of their lifeblood. Who is to prevent it from doing so? In France and Spain there are small but effective (and sometimes violent) regional movements. Should the rest of the country simply give in to them? Where lies the right answer between a Scottish solution and a Chechen non-solution?

The point of asking such questions is to remind ourselves that genuine constitutional politics requires serious thought and careful preparation. It must never be a substitute for the absence of other ideas. In that sense, Conventions such as the one led by former French President Valery Giscard d'Estaing for Europe are a good idea. They just might dissuade politicians who are bereft of ideas from indulging in pet projects that lead nowhere.