Why can courts in the United Kingdom interpret laws but not invalidate acts of Parliament?

In the United Kingdom, courts cannot invalidate acts of Parliament because the British political system is founded on the principle of parliamentary sovereignty. Under this constitutional theory, Parliament—comprising the House of Commons, the House of Lords, and the monarch—possesses the ultimate legal authority to enact or repeal any law, and no other body, including the judiciary, has the power to override or strike down its legislation.12

Unlike countries with a written constitution that serves as a supreme legal document, the U.K. lacks a single codified constitution. Instead, its constitutional framework has evolved through custom, tradition, and ordinary legislation. Because there is no higher constitutional law for Parliament to violate, the courts do not exercise the power of judicial review to invalidate statutes.13

While courts cannot strike down acts of Parliament, they do play a significant role in interpreting them. For instance, under the Human Rights Act 1998, courts are obligated to interpret legislation in a way that is compatible with convention rights whenever possible. However, this remains a process of interpretation rather than the power to invalidate the law itself.4