The validity of an arbitration clause must be evaluated autonomously from the contract to which it refers, according to Article 808 of the Code of Civil Procedure, and the power to stipulate the contract includes the power to agree the arbitration clause.
An arbitration clause inserted in a contract not by adhesion, but as the fruit of private negotiation, does not require specific and double signature under Article 1342 of the Civil Code, as the regulation of contracts concluded by means of standard forms does not apply.
Where there are conflicting arbitration clauses between the main contract and general contract terms, the special regulation agreed in the main contract prevails over the general regulation of the general terms, even when the latter have not been specifically signed under Article 1341 of the Civil Code.