It’s starting to become an annual event. A group of Germans claim that part of the euro bailout is illegal. The case reaches the German Constitutional Court. And then financial experts around the world sit on the edge of their seats, waiting to find out if this group of judges will destroy the euro.

It happened last September, and the September before that. Then on June 11 the court began yet another hearing after 37,000 German citizens complained. It’s expected to rule after the German election, which takes place in September.

This time though, the case revolves around the European Central Bank (ecb). Last August, when the euro crisis looked like it could take a turn for the worst, the ecb announced a new program to help prop up indebted countries. If an indebted country first submitted to the European Union’s conditions (read Germany’s conditions), the ecb would lend the government an unlimited amount of money in order to keep its borrowing costs down. In order to get around EU rules, it’s a little more complicated—it can’t buy the debt from the government directly, for example—but that’s the gist of its plan.

The theory is that investors would know that the country could never go bankrupt because the ecb would always lend it money, meaning that the investors would feel more confident about lending money. The program was called Outright Monetary Transactions (omt). So far it has succeeded. Borrowing costs for southern Europe have gone down, without the ecb having to do anything beyond make the announcement. It has not lent a single cent under omt.

But, quite understandably, a lot of people in Germany are concerned by the ecb’s promise to essentially print money and hand it over to governments that can’t pay their bills. One of these parties is the Bundesbank (Germany’s central bank), which is opposing the ecb in this court case.

Former Constitutional Court Judge Udo di Fabio published an opinion a few days ago where he said that if the court believed the ecb was acting far beyond its mandate, it “must decide whether Germany can remain a member of monetary union on constitutional grounds.” In the most extreme scenario, the court could rule that the ecb’s actions are incompatible with the German Constitution. This would leave Germany with three options: Persuade the EU to change; change the German Constitution; or leave the eurozone.

Such an extreme action is unlikely, but it could limit how involved the Bundesbank is with omt, which could cause the whole system to collapse. “[I]t would pull the rug from under the whole project. It is the omt alone that has calmed markets and saved the periphery,” Andrew Roberts from Royal Bank of Scotland said, according to the Telegraph’s Ambrose Evans-Pritchard.

“Over the past few months, Draghi and the heads of government in the European capitals have felt confident about the outcome of the impending ruling,” writes Der Spiegel. “After all, the judges in Karlsruhe have always ultimately endorsed Germany’s contributions to eurozone bailout programs. Nevertheless, the list of questions compiled by the judges for this week’s deliberations indicates that everything may be at stake this time around.”

The court’s decision has now become one of the biggest risks for the eurozone in the near future.

“When Draghi recently visited French President François Hollande in Paris, the main topic of discussion was not the state of the French economy or southern Europe, but rather the question of what will happen in Karlsruhe,” continues Spiegel, Karlsruhe being the location of the Constitutional Court. “Only one hour by train away from Frankfurt, a conflict is brewing that already appeared to have been resolved last autumn.”

“For the last few days, ecb head Draghi has constantly consulted with his aides on the latest developments of the debate in Karlsruhe and what people in Germany are saying about it,” it writes. Spiegel then quotes a court official as saying: “The people at the ecb are really afraid.”

Once again, the very existence of the euro is threatened and no one knows how it is going to turn out. The court case is already scaring investors in southern Europe. After the court began its hearings the Milan stock exchange, for example, fell by 1.63 percent.The judges’ line of questioning showed they were skeptical of the ecb’s measures. “The justices clearly have grave doubts about the legality of the omt program,” writes Spiegel.

As we’ve pointed out since the start of the crisis, the euro was designed to fail in order to force EU nations to unite. There are a whole number of ways the court’s decision could lead this along. But it is an important reminder that the drama in Europe is far from over. Europe is only part of the way toward integration. It will take more crises, as well as the involvement of the Catholic Church, to force the nations to unite.