Relational contracts are defined as the set of unwritten codes of conduct that affects parties behavior during a business. The existence of these 'contracts' is motivated by the impossibility of predicting all the contingencies that may occur after a formal agreement is stipulated. As widely recognized in the economic literature, the incompleteness of written contracts can give rise to opportunistic behaviors of a party, that reduce the margins for the conclusion of efficient transactions. The adverse selection, moral hazard and hold-up problems are typical examples of contractual...