Contract for the paid assignment of space with an arbitration clause. Contract drafted by the real estate agency, which designates the Câmara Imobiliária de Mediação e Arbitragem - CIMA for the resolution of disputes. Invalidity of the arbitration clause because "it is apparent that the said arbitration center is related to real estate agencies, which suggests the existence of possible bias" and because it is located in another city, which would hinder the exercise of the contracting party's right to a full defense: