It also follows an earlier — more effective — move from the European Parliament to refer the deal to the Court of Justice. Backed by MEPs in January, the case could delay the ratification of the full agreement for up to two years. In a bid to reap the deal’s benefit sooner, the European Commission will start applying its trade provisions from May 1. 

Poland’s parallel filing adds political noise, not legal firepower.

Deputy PM Władysław Kosiniak-Kamysz, leader of the farmer-friendly PSL party, broke the news, saying the complaint would target Mercosur’s impact on food security and the procedure used to push it through.

“We will challenge this agreement,” he said. “Food security is threatened, consumer protection is threatened, and the way the agreement was implemented is not correct.” 

Agriculture Minister Stefan Krajewski, tasked with preparing the complaint, said he hoped to file before May 1. However, he could not say what specific legal arguments Poland would make, what the complaint would achieve, or whether Warsaw would seek to suspend the deal’s provisional application. 

“We’re working on it,” he repeatedly told reporters at a hastily-organized press conference in Warsaw on Friday.

As recently as late March, Tusk had said the government saw no need to file its own complaint, arguing the Parliament’s referral was sufficient. Speaking on a plane from an EU summit in Cyprus, he said Friday he had warned the European Commission in advance.

“I told them nothing has changed about our critical assessment of certain aspects of Mercosur,” he said, adding that he asked Brussels “not to treat this as a personal attack.”