German Finance Minister Wolfgang Schäuble has urged the court to reach a decision soon on the European Stability Mechanism (ESM), but the president of Germany's Constitutional Court, Andreas Vosskuhle, has said the judges will take their time.

A "very thorough examination" was likely he said on Tuesday. Originally, the decision as to whether the ESM and the proposed fiscal pact on national budgets are contrary to the German constitution was expected by the end of July.

Watch video 01:37 German court debates ESM

Schäuble insisted that any delay would trigger "massive uncertainty on the markets" and "significant economic distortions."

Fierce opposition

Several groups have raised objections to the constitutionality of the measures, including one, Europe Needs More Democracy, which said its complaint had been lodged on behalf of 12,000 citizens.

Others objecting to the ESM in particular are former justice minister Herta Däubler-Gmelin and legal expert Karl Albrecht Schachtschneider.

The Left party want the Karlsruhe-based court to strike down the pro-austerity fiscal pact on the grounds that it would hamper parliament's ability to prevent spending cuts.

In the past, the court has proved sympathetic to arguments that parliament's powers must not be undermined by the need for speed.

"The Bundestag must remain at the center of political decisions, especially regarding its core competences such as responsibility for the federal budget," former Constitutional Court judge Udo di Fabio told this week's edition of the news weekly Der Spiegel.

The launch of the ESM, originally set for July 1, has been postponed. The impasse has meant a delay to the implementation of the mechanism, after the Constitutional Court asked President Joachim Gauck to not sign off on the legislation until a series of complaints about it had been addressed by its judges.

The fiscal pact was agreed to by 25 of the European Union's 27 member states, with Britain and the Czech Republic deciding not to become signatories.

ng, rc/sej(dpa, dapd, Reuters)