The granting of precautionary measures prior to the beginning of an arbitration, is essential to achieve the effectiveness of the future arbitral award. The current arbitration legislation allows judicial collaboration in this matter by regulating the opportunity for its dictation, as well as the grounds for its extinction. The termination of precautionary measures is closely related to the disappearance of the requirements for their concession, such as verisimilitude in law, danger in delay and adequacy. However, our legal system allows that a precautionary measure may be extinguished in case the arbitral tribunal is not constituted within a maximum period of 90 business days from its execution. In this sense, the purpose of this thesis is to analyze the reasonableness of this case of termination with a view to protecting the right to effective judicial protection. To this end, the vari...