222. It is thus common for an EDRS to provide for several types of challenge and several mechanisms for resolving them – the EMB, one or more judicial bodies and, on occasion, a legislative body. While EDR systems generally provide for different types of mechanism, all of them should be consistent with the principles and guarantees of EDR systems in order to ensure that all electoral actions, procedures and decisions are in line with the principles of constitutionality and legality. 223. In identifying the principles and guarantees of EDR systems, the intention is to establish parameters in keeping with international commitments and standards, ‘good practices’, and ‘minimum conditions’ required for considering an EDR system to be in line with the principles characteristic of constitutional democracy under the rule of law. It should be noted that identifying such principles and guarantees is not intended to inhibit other experiments or practices, as long as their purpose is to consolidate the holding of elections that are free, fair and genuine, and in keeping with the law. Commitments and standards are constantly evolving in both theory and practice. 224. Citizens, candidates, political parties, the media, the authorities and all those who play a role in electoral processes are expected to comply with electoral law voluntarily, of their own accord. However, an EDR system is needed to ensure the observance of the entire electoral law and to address those cases in which the law is violated. The EDR system is an essential form of support to ensure that electoral actions, procedures and decisions are in keeping with electoral and other law. 225. Among the measures aimed at ensuring that electoral challenges are resolved lawfully, there exist both structural guarantees and procedural guarantees. Structural guarantees are those legal instruments for ensuring that EDRBs act with autonomy, independence and impartiality (for example the procedure for selecting and appointing their members). Procedural guarantees are those legal measures that help to ensure that the mechanisms for bringing and resolving electoral challenges have attributes which promote electoral justice and ensure that the EDR system is both effective and efficient 85 6. Principles and guarantees of EDR systems of the EMB at a higher level. This organ generally has the power to correct the alleged irregularity. Once the official result with respect to an election is issued, several EDR systems provide for the right of political parties or candidates that are not satisfied to challenge it before a judicial body (regular, constitutional, administrative or electoral court). On occasion this judicial stage provides for a challenge first before a regular court of the judicial branch or an electoral court, and then before a constitutional court, which issues the final ruling. Some EDR systems still provide for the possibility of a subsequent challenge before the legislative body, which in such systems has the final decision on the validity of the election and its results.