Judicial review is one of the main characteristics of government in the United States and similar democratic countries. It can be understood in the context of two distinct but parallel legal systems (civil law and common law), and also by two distinct theories on democracy and how a government should be set up (the ideas of legislative supremacy and a separation of powers). First, two distinct legal systems, civil Law and common law have different views about judicial review. Though civil law has its root on Corpus Juris Civilis, other historical events affected its development over the last fifteen hundred years. For example, the French Revolution had a significant effect on how people from different countries felt about civil law traditions. In 1804, the Napoleonic code was created. Legislative supremacy (or parliamentary sovereignty) was one of the key ideas underlying the Napoleonic code of 1804. The idea of legislative supremacy is that the legislative body should be superior (and consequently more powerful) than other branches of government. The imbalance in power is justified by the legislative branch because the people elect their own state or regional legislatures. In addition, the judicial body is prohibited from creating or challenging laws created by the legislative branch. The lack of judicial review denies the judicial branch a check on the power of the legislative branch.
Secondly, the idea of separation of powers is another theory about how a democratic society's government should be organized. In contrast to legislative supremacy, the idea of the separation of powers was first introduced by French philosopher, Charles de Secondat, Baron de Montesquieu, and was later institutionalized in the United States by the Supreme Court ruling in Marbury v. Madison. The separation of powers is based on the idea that no branch of government should be more powerful than any other, and that each separate branch of government should have certain checks on the powers of the other branches of government; thus creating a balance of power among all the branches of government. The key to this idea is checks and balances. In the United States, judicial review is considered a key check on the powers of the other two branches of government by the Judiciary, (although the power itself is only implicitly granted). Thus overall, differences in organizing "democratic" societies led to different views regarding judicial review; with societies based on common law and those stressing a separation of powers being the most likely to utilize judicial review. Nevertheless, many countries where legal systems are based on the idea of legislative supremacy have since learned the possible dangers and limitations of putting so much power exclusively in the legislative branch of government. Many countries with civil law systems have since adopted some sort of judicial review in order to stem the tyranny of the influential.
Another reason why judicial review should be understood in the context of both the development of two distinct legal systems (civil law and common law) and the two distinct theories of democracy (legislative supremacy and separation of powers) is that some countries with common law systems nonetheless do not have judicial review. Though a common law system is present in the United Kingdom, the country still has a strong attachment to the idea of legislative supremacy and consequently the judicial body in the United Kingdom does not have any power of judicial review. However, since the United Kingdom became a member of EU, there has emerged a strong tension between the UK's national tendency of legislative supremacy and the EU's legal system which empowers the Court of Justice of the European Union with judicial review.
 Judicial review of administrative actsEdit
Most modern legal systems allow the courts to review administrative acts; i.e., individual decisions of a public body, such as a decision to grant a subsidy or to withdraw a residence permit. In most systems, this also includes review of secondary legislation; i.e., legally enforceable rules of general applicability adopted by administrative bodies. Some countries, most notably France and Germany, have implemented a system of administrative courts, that are charged exclusively with deciding on disputes between the members of the public and the administration. In other countries, including the United States, United Kingdom and the Netherlands, judicial review is carried out by regular civil courts, although it may be delegated to specialized panels within these courts, such as the Administrative Court within the High Court of England and Wales. The United States employs a mixed system in which some administrative decisions are reviewed by the United States district courts, which are the general trial courts, some are reviewed directly by the United States courts of appeals, and others are reviewed by specialized tribunals such as the United States Court of Appeals for Veterans Claims (which, despite its name, is not technically part of the federal judicial branch). It is quite common that before a request for judicial review of an administrative act is filed with a court, certain preliminary conditions, such as a complaint to the authority itself, must be fulfilled.
In most countries, the courts apply special procedures in administrative cases.
 Judicial review of primary legislationEdit
There are three broad approaches to judicial review of the constitutionality of primary legislation; that is, laws passed directly by an elected legislature.
Some countries do not permit any review of the validity of primary legislation. In the United Kingdom, statutes cannot be set aside under the doctrine of parliamentary sovereignty. Another example is the Netherlands, where the Constitution expressly forbids the courts to rule on the question of constitutionality of primary legislation.
In the United States, federal and state courts, at all levels, both appellate and trial, are able to review and declare the "constitutionality", or agreement with the Constitution—or lack thereof—of legislation that is relevant to any case properly within their jurisdiction. In American legal language, "judicial review" refers primarily to the adjudication of constitutionality of statutes, especially by the Supreme Court of the United States. This is commonly held to have been established in the case of Marbury v. Madison, which was argued before the Supreme Court in 1801.
A number of other countries whose constitutions do provide for a review of the compatibility of primary legislation with the constitution have established special constitutional courts that have the exclusive authority to deal with this issue: see List of constitutional courts. In these systems, other courts are not competent to question the constitutionality of primary legislation.
Brazil adopts a mixed model since, as in the U.S., courts at all levels, both federal and state, are empowered to review primary legislation and declare its constitutionality, and, as in Germany, there is a Constitutional Court in charge of reviewing the constitutionality of primary legislation. The difference being that, in the first case, the decision about the laws adequacy to the Brazilian Constitution only binds the parties to the lawsuit, whereas in the second, the Courts decision must be followed by all judges and government officials at all levels.