Resumen de Reconstructing the Jurist's Reasoning: 'Bona Fides' and 'Synallagma' in Labeo (D. 19, 1, 50)
The text of Labeo advances bona lides as a normative foundation of the mutual obligations arising from the contract of sale. In the last years this text was treated from a political and ideological perspective, while it seems to present an outstanding dogmatic reasoning that can be revealed through analysis of the jurist's argument as dealing specially with the legal construction of the interdependent contractual obligations (synallagma). The public act (lex publica) liberating the buyer from his duty to pay the price could only be a statute derogating all monetary debts (lex de novis tabulis). Since such lex is not known at the time of Labeo, the scholastic character of the case under discussion is supposed. The obligation of the buyer should have been previously transformed (novatio) through a special stipulation to become an independent monetary obligation that could be derogated by the lex publica. In general the effect that such a stipulation should have on the mutual obligations of the parties became the recurrent issue of Roman jurists' practical decisions since the second century BC. According to Varro, whose texts reflect the situation of the third and second century BC, the stipulated monetary obligation of the price did not substitute tbe contractual obligation of the buyer, but existed along with it. The texts written in the first century BC by Alfenus on this issue are ambiguous. Later on, the novatory effect of the stipulation of the price is beyond doubt. In the second century AD Julian tries to treat tbe monetary obligation of the buyer in line with the usual mutually conditioned obligation based upon tbe contract of sale. It seems that Julian is following the idea advanced by Labeo in D. 19, 1, 50 who defended tbe seller from the claim of tbe buyer relying on the mutual dependence of the obligations of the parties notwithstanding a previous novatio and a consequent violation of the synallagma. To sustain such an approach Labeo appeals to the bona fides principle governing the synallagmatic contracts. Being simply an element of the judicial formula of the contractual claim, bona fides in Labeo's decision becomes the material basis of the relationship and legal principle governing contractual obligations.
