The documents arrived at the Bundesverfassungsgericht on Wednesday: 70 bankers’ boxes containing more than 125,000 signed powers-of-attorney, passed from person to person along a human chain to the doors of the courthouse. The BVerfG, as it’s known for short, is Germany’s highest constitutional court, and the NGOs that delivered the documents to the court were filing what they claim is the largest constitutional challenge in the country’s history. Its goal is to stop the proposed free trade agreement between Canada and the European Union.

September could prove the pivotal month for the Canada and European Union Comprehensive Economic and Free Trade Agreement (CETA), and Germany could be the key battleground as the treaty’s fate is decided.