LIKE Lord Voldemort of Harry Potter fame, “treaty change” is an idea so terrifying that most Eurocrats dare not speak of it. So when Wolfgang Schäuble, Germany’s finance minister, declared recently that it was needed for the next move in tackling the euro crisis, Brussels gasped. What was Germany up to? It was surely no coincidence that, on the same weekend, Britain’s David Cameron was in Berlin to talk to Angela Merkel about reforming the European Union.

There was a time when treaty change was pushed only by enthusiasts for “ever-closer union” in Europe. Then small changes were made mainly to satisfy legalistic Germans. Nowadays those keenest on the idea are either wanting to slow down some aspects of integration, like Germany, or to reverse it, like Britain. Even before the crisis, the endless renegotiation of the EU’s rule-book had reached its limits. The last big rewrite took the best part of a decade: the constitutional treaty was rejected by French and Dutch voters in 2005, and its successor, the Lisbon treaty, had to be put to the Irish twice before passing. Today, even assuming that Europe’s debtors and creditors can agree, any revision could invite disaster. Much of the euro zone is in a deep and prolonged recession, and Eurosceptic parties of many stripes are on the rise in both north and south.

The euro zone is caught between volatile markets that demand action to fix the broken single currency and citizens, many of whom are hostile to a European project that seems to bring nothing but bail-outs and austerity. So Europe’s leaders will do almost anything to avoid submitting a treaty to voters. The European Central Bank has acted autonomously to prevent the break-up of the euro. EU rules have been modified within (and beyond) the limits of existing treaties. Euro-zone members are pushed by Brussels to cut deficits and reform their economies.

That said, Germany has forced through two treaty amendments, albeit “surgical” ones. The first was to permit the replacement of temporary euro-zone bail-out funds with the permanent European Stability Mechanism (it started operating months before the amendment was fully ratified). The second enshrined tougher budget rules (despite a British attempt to block it). The threat of losing EU funds then convinced Irish voters to endorse this fiscal compact in a referendum.

A bigger overhaul of the treaty is now being put off as long as possible. Over the past year EU leaders have squashed most ideas from Brussels for long-term reform, such as mutualised debt, a central euro-zone budget or greater powers to dictate national economic policies. Instead the focus has been on “banking union” that would entrust bank supervision and crisis management to European authorities. The aim is to stop craven national supervisors protecting their banks, and to sever the tie between weak banks and weak sovereigns. The fact that much of this could be done within existing treaties made the controversial banking union more palatable.

But no sooner had the idea been launched than Germany began a rearguard action. Its eleventh-hour legal objections to the creation of a single supervisor were overcome only after finance ministers declared their readiness “constructively” to consider an amendment, when a future treaty revision takes place, to strengthen the separation between the European Central Bank’s (ECB) monetary and supervisory functions.

Mr Schäuble then dug his next defensive trench: the creation of a European “authority” to restructure and wind up ailing banks, the obvious complement to the new supervisor, would require treaty change. Even the Germans’ closest allies, the Finns and the Dutch, were discomfited by his contradiction of the spirit, if not the letter, of a December summit deal calling for the establishment of a European resolution “mechanism”.

The Germans argue that there is no point in rushing a European resolution system when plans to create 27 national ones have yet to be approved. And whereas the treaties foresaw granting the ECB supervisory powers, they have no explicit provisions for a European body to deal with bust banks, especially one that involves committing taxpayers’ money. The European Commission insists this is compatible with current treaties, though some privately admit the legal base is open to question.

The charitable view is that Germany is merely the most purist of the EU’s members. The cynical one is that Germany is trying to block any move to share liabilities for Europe’s banks, or at least delaying until after its federal election this autumn. Mr Schäuble’s views should be treated as an opening position, not his final word. There may be room to fudge the distinction between the commission’s idea for a European “mechanism” and his notion of a “network” of national bodies.

The question that still has no answer

Germany says the EU should neither rush to revise the treaties, nor be afraid to do so when needed. As Dumbledore tells Harry Potter: “Fear of a name increases fear of the thing itself”. But the German tactic of incremental change may no longer work. Any treaty change is unlikely to remain small. It will be pulled from one end by the commission, which promises to present proposals next year to transform the EU into a “federation of nation-states”. From the other end, Britain has given notice that it will exploit any treaty change to demand reforms or renegotiate its relations with the EU ahead of a referendum by 2017.

The price for any repatriation of British powers, demanded by France, among others, is likely to be a more tightly integrated “core” euro zone. Sooner or later, treaty change will come. Germany and others may then have to answer the question they keep avoiding: what sort of union do they really want?

Economist.com/blogs/charlemagne