Poland and Hungary are challenging a new mechanism in the European Union's budget that links payments to rule-of-law conditions, for which both countries have come under heavy criticism.
The new mechanism was built into the 2021-27 spending plan and 750-billion-euro ($890-billion) stimulus fund meant to offset the effects of the coronavirus pandemic on the economies of the 27-member bloc.
The conditionality allows disbursements to be withheld if there are certain violations of basic standards, such as the undermining of judicial independence.
The measure has been opposed by Poland and Hungary, both of which have been severely criticized by the EU over rule of law.
The two countries had blocked the adoption of the EU budget and coronavirus recovery package over the dispute.
At an EU summit in December, EU leaders reached a compromise that meant the mechanism would not be implemented until the European Court of Justice has ruled on any possible complaints.
Poland announced on March 11 that it had filed a complaint with the court against the measure.
"We believe that such solutions have no legal basis in the treaties, interfere with competences of member states and infringe on EU law," government spokesman Piotr Mueller said in a statement.
"Disbursement of funds from the EU budget should be based only on meeting objective and concrete conditions, which unequivocally stem from regulations," Mueller said.
In Budapest, Prime Minister Viktor Orban’s chief of staff, Gergely Gulyas, said Hungary will launch a similar court case this week.
"We are challenging the rule on conditionality before the Court of Justice of the European Union, together with Poland," Justice Minister Judit Varga said on Facebook.
"We can't keep that EU legislation in force, which seriously infringes legal certainty," she said.