The power of courts to assess whether laws or executive acts conflict with a constitution or higher law, and to refuse to apply them if they do.
In more detail
In the United States it was asserted in Marbury v. Madison (1803), where Chief Justice Marshall wrote that it is the province and duty of the judiciary to say what the law is. Many countries use specialised constitutional courts, such as Germany's Federal Constitutional Court. In weak-form systems, such as the UK under the Human Rights Act 1998, courts may declare a law incompatible with rights without invalidating it. Critics argue that unelected judges override legislatures; defenders stress protection of rights.