387. In countries with a civil law tradition, the important function attributed to written law as the main source of law, combined with the principle of judicial independence which requires that a judge is generally subject only to the mandate of written law and not to rulings made by another judge, together mean that in most of these countries judicial precedent is not binding on future cases. This is the case, for example, in France. However, in some systems this is changing, and an increasing number of systems (judicial systems in general and EDR systems in particular) in this tradition provide that precedents established by certain judicial bodies are binding on lower courts. 388. Thus, for example, the Superior Chamber (Sala Superior) of the Electoral Court of the Judicial Branch of the Federation of Mexico is authorized to establish binding case law when it upholds the same standard for interpreting or filling gaps in the law in three judgements. Unlike other systems (both common law and civil law) in which precedent or case law is binding only on judicial bodies, in Mexico the case law established by the Superior Chamber of the Electoral Court binds all other electoral courts (both the lower-ranking ones of the federal judiciary and the state electoral courts) and also the EMBs (both the federal EMB and those that correspond to each state of the federation). The law also provides that the Superior Chamber may undo the binding nature of the case law by a majority of five of its seven members, specifying the reasons that justify the change in its interpretative criteria. 389. In general, the top-level organ of any EDR system should endeavour to establish clear and uniform criteria for interpreting the applicable constitutional and statutory provisions and for filling any possible legal gaps if it has the authority to do so. In addition, it should establish and disseminate the set of judicial precedents that may be binding on the lower EDRBs. It would also be desirable for the electoral legislation to establish that such precedent is binding on the EMBs, as differences in the application of criteria between different electoral authorities could pose a threat to legal certainty and imperil trust in the electoral process and its institutions. This is part of the so-called normative autonomy that characterizes the various EDR systems. It is advisable that each EDR system is regulated by clear and precise provisions. 132