The object of this study is the survival of the principles that govern the onus probandi and the way they do it in classical and post-classical Roman law and in Spanish law; in particular, the inquisitorial principle in Visigothic law (Edict of Euric, Breviary of Alaric and Lex Visigothorum) and the principle of free production of evidence, from a structural point of view, in the medieval Valencian source: els Furs.


Keywords: Roman law; onus probandi; furs; Inquisitorial principle; unfettered evaluation of evidence; Visigothic law.