From the original 12 founders of the breakaway competition, the trio are the only ones who still want a European Super League and have refused to withdraw their support for the project.
In a statement released, the European giants have insisted that they are "well within their rights to start a new competition" and have claimed that UEFA and FIFA have "no right to get in their way".
UEFA and FIFA have publicly opposed the new league, with football's governing body already beginning disciplinary proceedings against the three clubs.
UEFA have announced that they are delaying potential punishments for Barcelona, Real Madrid, and Juventus for their role in the creation of the ESL
Iker Casillas has admitted he is hopeful that his former club Real Madrid can reach an agreement with Sergio Ramos.
Real Madrid could use Atletico Madrid's Wanda Metropolitano as their home venue for the 2021-22 domestic season.
A UEFA spokesperson said: "Following an investigation conducted by UEFA Ethics and Disciplinary Inspectors in connection with the so-called ‘Super League’ project, disciplinary proceedings have been opened against Real Madrid CF, FC Barcelona and Juventus FC for a potential violation of UEFA’s legal framework. Further information will be made available in due course."
"UEFA takes note of the announcement by the European Court of Justice of the referral from a Madrid court on the so-called European Super League, notwithstanding the withdrawal of nine of its founding member clubs. UEFA is confident in its position and will defend it robustly."