The first and most immediate effect of an arbitration agreement is the obligation that is created between the parties to honour the commitment to bring the disputes that may arise in their legal relationship before a third party. Now then, the sole will of the parties can never erase the right of said parties to have access to the Courts. The right to effective judicial protection as a fundamental right is inalienable for its unavailability. The Constitution’s system of rights and liberties cannot be derogated by its own beneficiaries. With this reflection in mind, the author analyses the legal justification of the preventive effect that arbitration has on the Courts, so that the intangibility of constitutional law for judicial protection is maintained.