What Is a Constitutional Monarchy?

LONDON — One topic was at the heart of King Charles III’s address to the British Parliament on Monday, and, many experts would say, of almost all his public statements and actions since the death of Queen Elizabeth: upholding Britain’s system of constitutional monarchy.

He ended his speech by recalling his mother’s promise to “maintain the precious principles of constitutional government which lie at the heart of our nation,” and by vowing to follow her example.

For some foreign observers, that has raised the question: How can you have a constitutional monarchy when you don’t have a written Constitution?

While Britain does not have a single constitutional document like the one ratified by the United States in 1788 — or the one rejected by Chilean voters earlier this month — it still has laws and carefully documented traditions that together form a Constitution, one that binds the king.

These rules have accumulated in centuries of legislation and a surrounding mass of convention. (The explanation of Britain’s constitutional monarchy provided by the House of Lords Library begins with Magna Carta in 1215, and the initial restraints on royal power, and continues though a thicket of legal dates to 1701, when Parliament intervened in the royal succession.)

Together, they make the king a constitutional monarch: an embodiment of power and statehood with no personal public role in politics, and tight constraints even on private influence.

Charles acknowledged those conventions to lawmakers by beginning with praise of “vital parliamentary traditions,” linking them to the vaulted medieval timber roof of Westminster Hall, the parliamentary building in which he spoke.

Constitutional traditions came under some strain in Parliament in recent years, as Prime Minister Boris Johnson sought to drive through his legislation on leaving the European Union. One use of executive powers, a weekslong suspension of Parliament, drew a rebuke from Britain’s Supreme Court.

“Our constitution basically depends on very British sentiments of decency and fair play, and it assumes people who reach high office will respect conventions, precedents and unwritten rules,” Professor Meg Russell, the director of the Constitution Unit at University College London, told The Times in 2019.

The queen, by contrast, maintained the popularity of the monarchy in part by what her son described to lawmakers on Monday as “unsurpassed devotion” to a tradition of restraint.

That’s one reason that Charles raised eyebrows in his long decades as Prince of Wales. He publicly championed what might otherwise have seemed an innocuous set of causes: the environment, organic farming, complementary medicine, traditional architecture. He touched on the matter in his very first address as monarch last week, saying: “It will no longer be possible for me to give so much of my time and energies to the charities and issues for which I care so deeply.”

He would leave all that, he said, “in the trusted hands of others.” After the example of his mother, it may be what the British Constitution has come to require.