Barcelona, Real Madrid and Juventus have released a joint statement in defiance of threats from UEFA over their Super League attempt.
The three clubs remain steadfast in their desire to create a Super League and have released a joint statement on Wednesday with the intention of getting UEFA president Aleksander Ceferin to take a step back.
A Champions League ban has been floated as a possible penalty.
The statement said: "FC Barcelona, Juventus FC and Real Madrid CF wish to express their absolute rejection of the insistent coercion that UEFA has been maintaining towards three of the most relevant institutions in the history of football. This alarming attitude constitutes a flagrant breach of the decision of the courts of justice, which have already made a clear statement warning UEFA to refrain from taking any action that could penalise the founding clubs of the Super League while the legal proceedings are ongoing.
"Therefore, the opening of disciplinary proceedings by UEFA is incomprehensible and is a direct attack against the rule of law that we, the citizens of the European Union, have democratically built up, while constituting a lack of respect toward the authority of the courts of justice themselves.
"From the beginning, the Super League has been promoted with the aim of improving the situation of European football, through permanent dialogue with UEFA and with the objective to increase the interest in the sport and to offer fans the best possible show. This objective has to be achieved in a framework of sustainability and solidarity, especially in a precarious economic situation such as the one many clubs in Europe are currently experiencing.
"Instead of exploring ways of modernizing football through open dialogue, UEFA expects us to withdraw the ongoing court proceedings that question their monopoly over European football. Barcelona, Juventus and Real Madrid, all of them more than a century old, will not accept any form of coercion or intolerable pressure, while they remain strong in their willingness to debate, respectfully and through dialogue, the urgent solutions that football currently needs.
"Either we reform football or we will have to watch its inevitable downfall."