Constitutional Review is the process through which constitutional requirements are applied to legislation, governmental action or other legal measures to determine whether they comply with a constitution. Its underlying premise is constitutional supremacy, meaning that ordinary governmental institutions must act within the limits established by higher constitutional law. Constitutional review can concern legislation, executive regulations, administrative decisions, constitutional powers, institutional competences and, in some systems, omissions by public authorities.
If a court concludes that a legal rule conflicts with the constitution, the consequence may include invalidation, disapplication, reinterpretation, suspension of invalidity or another constitutionally prescribed remedy. The precise mechanism differs substantially between countries. Some systems centralise constitutional review in a dedicated Constitutional Court, while others allow ordinary courts to review constitutional questions. Constitutional review may therefore be concentrated or diffuse, abstract or concrete, preventive or subsequent. International constitutional practice treats these mechanisms as important methods for enforcing constitutional supremacy and protecting constitutional principles and rights. Constitutional review is not simply ordinary statutory interpretation because its distinctive question concerns compatibility with higher constitutional norms.
Constitutional Review can occur through several procedural models. Concrete review arises from an actual dispute in which the constitutionality of a legal rule matters to the resolution of a case. Abstract review examines a legal provision without necessarily requiring an individual dispute, often following a referral by specified political actors or institutions. Ex ante review takes place before legislation enters into force, whereas ex post review occurs after enactment.
Some systems permit individuals to bring constitutional complaints alleging that public action has violated constitutional rights. Others allow ordinary judges to refer constitutional questions to a specialised constitutional court. These procedures determine who can access constitutional review, when a challenge can be brought and what kinds of questions a reviewing institution may decide. Access rules are therefore an important component of constitutional design. If standing requirements are extremely restrictive, constitutional violations may be difficult to challenge.
If access is unrestricted, courts may receive large numbers of politically or legally complex claims. Constitutional systems consequently develop procedural filters, jurisdictional rules and remedies that shape the practical reach of constitutional review. Comparative constitutional guidance identifies forms of review, access, jurisdiction and remedies as central design questions.
The distinction between Constitutional Review and ordinary judicial review is important because terminology differs between legal systems. In some literature, judicial review is used broadly to include review of legislation for constitutional compliance, while in other contexts constitutional review is treated as a specific form of judicial review concerned with constitutional norms. Constitutional review can also be performed by institutions that are not ordinary courts, depending on the constitutional system.
The American model is commonly described as decentralised because courts exercising ordinary judicial functions can consider constitutional questions, whereas the European model traditionally associated constitutional review with a specialised Constitutional Court possessing centralised authority. These models are ideal types rather than exact descriptions of every country. Many contemporary systems combine characteristics from both approaches. A Supreme Court may function as the highest appellate court while also exercising constitutional jurisdiction, and ordinary courts may participate in constitutional litigation through referrals. The key analytical distinction is therefore not simply the name of the institution but where constitutional authority is located, how disputes reach the institution and what legal effect its decisions possess.
Constitutional Review can protect constitutional rights by examining whether legislation or executive action infringes protected freedoms or equality guarantees. A reviewing court may assess whether an interference has a legitimate legal basis, pursues a constitutionally acceptable purpose and satisfies whatever proportionality, reasonableness or limitation standard the constitutional system applies. Different constitutions formulate these tests differently. Some rights are absolute or subject to narrow exceptions, while others are subject to specified limitations.
Review can also protect structural constitutional principles that are not individual rights, such as separation of powers, federal competence or procedural requirements for legislation. Consequently, constitutional review is broader than human rights adjudication. A court might invalidate legislation because Parliament or another legislature lacked competence to enact it, because the required legislative procedure was not followed, because the measure violates an institutional principle or because it infringes an individual right. Constitutional review therefore operates simultaneously as a rights protection mechanism and as a system for maintaining constitutional structure.
Remedies are a particularly important feature of Constitutional Review. A court may declare legislation invalid, refuse to apply it to a particular case, interpret it consistently with the constitution, suspend the effect of invalidity to allow the legislature time to respond, or issue another remedy authorised by constitutional law. The effect can be prospective or retrospective depending on the jurisdiction.
Some constitutional courts can remove unconstitutional provisions from the legal order, while other courts may only decline to apply a rule in the case before them. Constitutional systems can also distinguish between the invalidity of an entire statute and the invalidity of a particular provision. Remedial choices affect the relationship between courts and legislatures because a declaration of incompatibility or unconstitutional application may leave lawmakers responsible for determining the precise legislative response. Comparative constitutional practice emphasises that the legal consequences of constitutional court decisions vary between jurisdictions and are often regulated by constitutional or statutory provisions.
Constitutional Review also performs an institutional function by maintaining the hierarchy between constitutional law and ordinary governmental action. Legislatures normally possess authority to make laws, executives administer them and courts resolve legal disputes, but constitutional review establishes that each institution remains subject to constitutional limits. This can prevent a temporary political majority from exercising powers that the constitution reserves or prohibits. Review can therefore reinforce separation of powers and checks and balances.
At the same time, constitutional review creates questions about judicial authority because unelected judges may invalidate decisions made by elected representatives. Constitutional systems respond differently to this issue through appointment procedures, standing rules, legislative override mechanisms, constitutional amendment procedures and limits on judicial jurisdiction. The existence of constitutional review does not eliminate political disagreement. Courts may disagree about interpretation, and political institutions may respond through legislation or amendment where the constitution permits. Constitutional review is consequently part of a wider institutional system rather than an isolated judicial power.
A common misconception is that Constitutional Review always means that a court simply cancels any law it considers undesirable. In reality, constitutional review is structured by jurisdiction, procedural rules, constitutional text, precedent and recognised standards of interpretation. Courts can uphold legislation, interpret it narrowly, identify incompatibility without immediate invalidation, or invalidate only particular provisions. Another misconception is that constitutional review always involves an individual rights complaint.
Structural disputes between government institutions, disputes concerning territorial competence and questions concerning electoral arrangements can also be constitutional. Review may likewise be preventive rather than reactive. The scope of review depends on the constitution and implementing legislation. A further distinction concerns political review. Legislatures and executives may conduct their own constitutional assessments when drafting or enforcing laws, while courts provide authoritative adjudication where judicial review is constitutionally established. Effective constitutional review therefore involves legal standards, institutional competence, procedural access and compliance with decisions rather than simply the abstract existence of a constitutional court.
Constitutional Review has become a central feature of many contemporary constitutional systems because constitutions increasingly contain detailed institutional rules and rights guarantees. Its effectiveness depends on judicial independence, access to courts, clarity of constitutional norms, institutional capacity and compliance by public authorities. A formally powerful reviewing institution can be ineffective if its decisions are ignored, while a court with more limited formal remedies can exert substantial influence through authoritative interpretation.
Constitutional review also evolves as constitutional texts are interpreted in changing social circumstances. The fundamental issue is the maintenance of constitutional supremacy while preserving a workable relationship between courts, legislatures and executives. Comparative constitutional analysis therefore studies not only whether review exists but who can initiate it, what can be reviewed, which standards are used, what remedies are available and how political institutions respond.
