The prime minister's move comes during a turbulent period for his government, which took power after last September's elections. Australia's attorney general, George Brandis, awkwardly declared that "people have the right to be bigots" during a Senate debate this week on the government's plan to repeal parts of the Racial Discrimination Act. Last week, the government's assistant treasurer stepped aside amid a widening corruption probe in New South Wales. "The focus on this right now shows the government has its priorities all wrong," said Labor deputy leader Tanya Plibersek in a radio interview.

The move also threatens to re-open a national debate about the future of the monarchy. Australian Communications Minister Malcolm Turnbull, a prominent leader of the country's republican movement, which wants to abolish the monarchy, tried to assuage the fears of fellow republicans by observing that "most countries have an honours system and many of them have an order of knighthood," including France, Italy, Peru, Argentina, and Guatemala. France still calls its lowest rank in the Légion d'honneur "chevaliers" despite abandoning monarchy in the 19th century, for example.

But while some republics do retain modernized forms of knighthood, traditional knighthoods are exceedingly rare. Today, only Antigua and Barbuda, Barbados, New Zealand, the United Kingdom, and now Australia—all realms of Queen Elizabeth II—maintain honors that entitle recipients to the honorific "Sir" or "Dame." Foreigners can also be made knights and dames in the Order of the British Empire but can't use the honorific, and they swear no allegiance to the Queen.

Foreign heads of state are the most frequent recipients of these highest awards, which can cause controversy. Elizabeth II stripped Robert Mugabe, Zimbabwe's autocratic president, of his honorary knighthood in 2008 for his abysmal human-rights record. Romanian dictator Nicolae Ceauşescu also lost his honorary British knighthood on Christmas Eve in 1989 during the bloody Romanian revolution, one day before his execution by a revolutionary tribunal.

"This is not Game of Thrones," Green Party MP Adam Bandt told reporters on Tuesday. "It shows a government bereft of ideas, and a social policy that isn't even stuck in the last century, it's stuck centuries ago."

The United States—a republic with a strong anti-monarchical and anti-aristocratic tradition— honors distinguished Americans and foreign citizens with the Presidential Medal of Freedom, the Congressional Gold Medal, and other lesser awards. Article I of the Constitution forbids establishing any "title of nobility" in the United States and bars U.S. citizens from accepting offices and titles "from any king, prince, or foreign state" without the consent of Congress. Even the president of the United States is simply called "Mr. President," although John Adams briefly proposed the title "His High Mightiness, the President of the United States and Protector of Their Liberties." It didn't stick.