Judicial review

Judicial review is a process under which a government's executive, legislative, or administrative actions are subject to review by the judiciary. In a judicial review, a court may invalidate laws, acts, or governmental actions that are incompatible with a higher authority. For example, an executive decision may be invalidated for being unlawful, or a statute may be invalidated for violating the terms of a constitution. Judicial review is one of the checks and balances in the separation of powers—the power of the judiciary to supervise (judicial supervision) the legislative and executive branches when the latter exceed their authority.

The doctrine varies between jurisdictions, so the procedure and scope of judicial review may differ between and within countries. The judiciary in United States has been described as having unusually strong powers of judicial review from a comparative perspective.

Judicial review can be understood in the context of two distinct—but parallel—legal systems, civil law and common law, and also by two distinct theories of democracy regarding the manner in which government should be organized with respect to the principles and doctrines of legislative supremacy and the separation of powers.

First, two distinct legal systems, civil law and common law, have different views about judicial review. Common-law judges are seen as sources of law, capable of creating new legal principles, and also capable of rejecting legal principles that are no longer valid. In the civil-law tradition, judges are seen as those who apply the law, with no power to create (or destroy) legal principles.

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 separation of powers was first introduced by Montesquieu; it was later institutionalized in the United States by the Supreme Court's ruling in Marbury v. Madison that the court had the power of judicial review to enforce the separation of powers stated in the US Constitution. This was left uncontested by the U.S. Congress and president Thomas Jefferson, despite his expressed opposition to the principle of judicial review by an unelected body.

Separation of powers is based on the idea that no branch of government should be able to exert power over any other branch without due process of law; each branch of government should have a check on the powers of the other branches of government, thus creating a regulative balance among all 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.

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.^{[citation needed]} Nevertheless, many countries whose legal systems are based on the idea of legislative supremacy have gradually adopted or expanded the scope of judicial review, including countries from both the civil law and common law traditions.

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 two theories of democracy (legislative supremacy and separation of powers) is that some countries with common-law systems do not have judicial review of primary legislation. Though a common-law system is present in the United Kingdom, the country still has a strong attachment to the idea of legislative supremacy; consequently, judges in the United Kingdom do not have the power to strike down primary legislation. However, when the United Kingdom became a member of the European Union there was tension between its tendency toward legislative supremacy and the EU's legal system, which specifically gives the Court of Justice of the European Union the power of judicial review.