Judicial review is the judiciary’s most powerful tool for enforcing the Constitution against elected officials.

Diagram of separation of powers and checks and balances in the U.S. system. It helps you see judicial review as one part of a larger set of institutional tools that prevent any one branch from dominating. Use it to connect court power to the broader logic of constitutional checks. Source

By deciding real disputes, courts can invalidate laws or executive actions that exceed constitutional limits.

What Judicial Review Is

Judicial review is exercised when a court assesses whether a law or executive action is consistent with the U.S. Constitution. If not, the court can refuse to enforce it, effectively blocking the political branches from carrying out that policy.

Judicial review is not explicitly written as a single clause in the Constitution; it is derived from the judiciary’s duty to decide cases under a supreme Constitution and has been affirmed through long-standing practice.

How Judicial Review Checks the Political Branches

Checking Congress (the Legislative Branch)

When Congress passes a statute, federal courts may later evaluate it during litigation. If a court finds the law conflicts with the Constitution, it can declare it unconstitutional and prevent its enforcement.

Key ways this checks Congress:

• Enforcing constitutional boundaries: Courts can stop Congress from exercising powers it does not have (for example, going beyond enumerated powers or violating protected rights).

• Protecting minority rights: Even popular laws can be invalidated if they violate constitutional protections.

• Constraining legislative “workarounds”: If Congress attempts to accomplish indirectly what it cannot do directly, courts may strike down the statute’s structure or application.

Judicial review therefore discourages lawmakers from ignoring constitutional limits, since unconstitutional policies can be overturned after passage.

Checking the President and the Executive Branch

Courts can also review executive actions—such as enforcement decisions, executive branch directives, or other presidential actions—when those actions create legal harm that can be challenged in court.

Key ways this checks the president:

• Limiting unilateral action: Courts can block executive actions that exceed constitutional authority.

• Requiring lawful administration: If executive implementation conflicts with constitutional requirements, courts may halt or narrow that implementation.

• Preserving separation of powers: Courts may invalidate executive actions that effectively make law without proper constitutional or statutory authority.

Because executive power can move quickly, judicial review can be especially significant when the president acts without new legislation.

What Courts Actually Do When They Exercise Judicial Review

Judicial review operates through judicial remedies and authoritative interpretation, including:

• Invalidation: A court may hold a statute or executive action unconstitutional, preventing it from being applied.

• Narrowing constructions: A court may interpret a law in a way that avoids constitutional conflict, limiting how the political branches may apply it.

• Orders affecting enforcement: Courts can direct government officials to stop enforcing an unconstitutional rule in the context of the case before them.

These outcomes make judicial review a practical check: it does not merely express disagreement; it changes what the government is legally permitted to do.

Why Judicial Review Matters for Separation of Powers

Judicial review supports the constitutional design by ensuring:

• The Constitution remains supreme over ordinary politics.

• The political branches cannot be the sole judges of the limits on their own power.

• Individual rights are protected even when elected officials face strong incentives to prioritise short-term political goals.

In this sense, judicial review is a stabilising mechanism: it channels constitutional disputes into legal reasoning and precedent, rather than leaving constitutional meaning entirely to electoral winners.

Limits Built into Judicial Review (Why It Is a Check, Not Control)

Although powerful, judicial review does not mean courts run the government. In practice, the check is shaped by constraints such as:

• Courts typically act after a law or executive action has affected someone, because review arises in disputes brought to court.

• Courts depend on other actors to follow rulings, so the check often works best when compliance is broadly accepted.

• Courts can block unconstitutional options, but they usually cannot force the political branches to adopt a particular policy alternative.

These limits help explain why judicial review is best understood as a constitutional backstop against overreaching, not a substitute for policymaking by elected branches.