A standard of proof, as per Black's: The degree or level of proof demanded in a specific case, such as "beyond a reasonable doubt" or "by a preponderance of the evidence." See BURDEN OF PERSUASION. This concept is so essential to the Anglo-Saxon understanding of law that it can be difficult to describe it, and to conceive of a judicial system without it. It could perhaps be described as the minimum level by which a case can be considered to be proven, based on the wording of the law (be it statutory or case law). When reading Spanish-language discussions of the concept, you will encounter the term umbral used to describe this idea: a "threshold for proof". While this concept does not exist as such in civil law countries, it is beginning to be imported, and is frequently described using a very literal phrasing, "estándar de prueba". See, notably, Los estándares de prueba en el proceso penal español, Jordi Ferrer Beltrán, Estándares probatorios en el sistema acusatorio y su desarrollo en Colombia, Claudia Edith Velandia Coy, Aplicación del estándar de prueba por los jueces promiscuos, autores varios.