"If I hear the word Karlsruhe one more time, I'm leaving the room." That's what International Monetary Fund (IMF) head Christine Lagarde is reported to have threatened a few weeks ago. But the court's influence is unavoidable at the moment. For one thing, its judges have a clearly designated and central role in interpreting the German constitution. For another, their decision about the legality of the European Stability Mechanism (ESM) within the most powerful EU country's legal framework will have a profound effect on the shape of eurozone rescue plans.

The implicit criticism in Lagarde's statement - that the judges in Karlsruhe have too much influence over the work of government leaders - goes back as far as the history of the court itself. Horst Ehmke, a legal scholar and former chief of the German Chancellery, is said to have exclaimed in 1973 that he was not going to let "those assholes in Karlsruhe" stand in the way of Germany's Ostpolitik policy towards Eastern Europe. The vehemence of Ehmke's words was telling - as was his perception of the court's Europe-wide significance.

'Monastery' atmosphere

Ensuring compliance with the constitution - that's the legal task of the Constitutional Court, which was established in 1951 in Karlsruhe. It consists of two senates with eight judges each, selected by the two houses of the German parliament. They serve 12-year terms, which correspond to three normal legislative periods. That, together with the court's geographical distance from Berlin, helps to ensure that the judges are separated from the daily business of government.

The Karlsruhe court is "one of the very few places in which decisions can be thought through in ways as intensely shielded from external influences as necessary," said Andreas Vosskuhle, president of the court's second senate, recently. That lends his place of work an atmosphere which is "almost like a monastery."

Ultimate legal authority

Constitutional Court judges can quite possibly have the last word in important national affairs. They can even reject laws which have been passed with a two-thirds majority in parliament. But as with any other court, the judges can only get involved in a case once they've been called upon to do so. The Bundestag, for example, can call upon the court to determine whether a law is constitutional.

The judges also have a role as mediators, for example, when there's a legislative dispute between German states and the federal government. And the court may examine the integrity of elections or - in one of its most powerful functions - outlaw political parties, as it did in 1952 and 1956.

Citizens have the right to file complaints with the court, as has taken place in the current closely watched case involving the legality of the ESM treaty. With 37,000 signatures, it represents the biggest constitutional appeal in the country's history.

Referees in the political 'game'

Karlsruhe is not just a court, though. Along with the Bundestag (the lower house of parliament), the Bundesrat (the upper chamber), the federal government and the president, it represents what is called a Verfassungsorgan (organ of the constitution) in legal terminology. That means its rights and duties stand fixed in the federal constitution. Among them: The judges must operate independently and impartially. But they do not enter the legislative process by enacting their own laws.

When asked about his influence on the government in Berlin, Andreas Vosskuhle said his court "isn't like a substitute player that comes in to show the team how you're really supposed to shoot a goal. Instead we're the referees of the political game."

From 1951 to 2011, a total of 457 federal laws and legal ordinances have been ruled as "fouls" by the court. Additionally, there have been a number of cases in which laws were only permitted to stand because the judges prescribed certain interpretations or formulations.

Karlsruhe's recent decisions involved setting the level of welfare payments made to asylum seekers, rejecting a special parliamentary committee on the euro, overturning preventative detention for dangerous felons and rejecting a reform of German voting laws. The more verdicts the court renders, the greater its influence on politicians' behavior and citizens' lives.

And that means the media now closely follow the court's decisions, pushing Karlsruhe's judges into a position of power.

Highly regarded

German citizens are happy to see this, as a recent study by the Allensbach polling firm showed. Two-thirds of the population are convinced that the court exercises a large or even very large degree of influence, compared to 48 percent in the 1990s.

Those surveyed said they think the court's standing is a good thing. 82 percent view it as an indispensible form of oversight. That's due in part to the eurozone crisis, said the head of Allensbach, Renate Köcher. Half of the respondents said they are worried the European integration process is gradually hollowing out the legitimacy of the German constitution.

"In this context, the Constitutional Court seems to many to be a stronghold that protects national interests," she said.

The belief that the court's judgments reflect citizens' own views has also grown, Köcher added, exempting the court from a more general trend in Germany toward skepticism towards the country's institutions.