Royal Decree

In the name of the Immortal God-Emperor and by the grace of the Golden Throne, I hereby declare Exterminatus on the Imperial world of Typhon Primaris, thereby consigning a billion souls to the Void.

The Emperor protects.

—Exterminatus Fleet, Dawn of War II: Retribution

A formal and ritualized decree is a common device in fiction, used to add a sense of grandeur to otherwise simple proceedings. These often begin with a reference to the person(s) promulgating the decree, and might even spell out all the titles they hold. What follows is usually either a generally applicable instruction or a list of demands. In either case, the decree has the force of law.

As the name of this trope suggests, such decrees are usually made by or in the name of a sovereign ruler. Rulers may utter their decrees personally (particularly when the decision is a reaction to a specific incident or discussion in their presence), often with a noticeable alteration of their voice. Alternatively, they may have it read out by someone specifically charged with the task.

In some cases, a decree of this legally-binding sort is issued by a group of people, such as a regency council that governs in the name of a child or an incapacitated ruler. Other groups issuing such decrees include town councils of free cities and religious authorities of The Church (especially of the fantastic variety).

Can overlap with Balcony Speech.

Examples of Royal Decree include:

Anime and Manga

In Dance in the Vampire Bund, Mina Tepes, queen of the vampires, uses this to kill a lesser vampire.

Film

The Wizard of Oz (1939). The Wizard gives instructions to the people of the Emerald City just before he takes off in his balloon.

Wizard: And I hereby decree that until what time, if any, that I return, the Scarecrow, by virtue of his highly superior brains, shall rule in my stead, assisted by the Tin Man, by virtue of his magnificent heart, and the Lion, by virtue of his courage! Obey them as you would me!

Disney's Cinderella (1950). The Duke reads a decree.

Grand Duke: All loyal subjects of his Imperial Majesty are hereby notified by royal proclamation in regard to a certain glass slipper. It is upon this day decreed that a quest be instituted throughout the length and breadth of our domain, the sole and express purpose of said quest to be as follows: That every single maiden in our beloved kingdom, without prearranged exception, shall try upon her foot this aforementioned slipper of glass. And should one be found upon whose foot said slipper shall properly fit, such maiden shall be acclaimed the object of this search and immediately forthwith shall be looked upon as the one and only true love of His Royal Highness, our beloved son and heir, the Noble Prince. Said Noble Prince will humbly and upon bended knee beg, request, or if need be, implore said maiden, that they grant her hand in marriage. Whereupon, should the aforementioned maid look with favour upon his suit, then shall the happy couple pledge their troth. And in due course, upon the inevitable demise of His Most Gracious and August Majesty, the King, succeed to the throne, there to rule over all the land as King and Queen of our beloved kingdom.

In the Santa Claus is Comin' to Town, Burgermeister Meisterburger makes a decree that outlaws Toymakers and toys in a Ruritania-like town. Because he's a jerkass (and in charge for some reason, even though we don't really know what his position or status is).
Gulliver's Travels features it in the first part.
The cut-off decree in Shrek counts.
Film Example: In Nosferatu (1922), the town council decrees people are forbidden from transporting plague victims to the hospital to avoid spreading the disease. Since it's a silent film, a town crier is shown banging a drum, and the proclamation is shown on a Title Card.

Literature

In David Eddings' The Elenium series, Sir Sparhawk presents a document to the Royal Council:

Sparhawk: It has the queen's signature on it and her personal seal.
[The document is later handed to Primate Annias.]
[The primate took the parchment in both hands as if he would tear it in two.]
"What's the penalty for destroying a royal decree, my Lord of Lenda?" Sparhawk asked mildly.
Earl of Lenda: Death.

Kelson dictated terms to the Mearan Pretender in The King's Justice in one of these. Dhugal (who was related to her by marriage) entered Laas and read the decree to her and her advisors. He was frequently interrupted by questions from Caitrin and Judhael about the fates of their kin in the Mearan army.

Tabletop RPG

Dungeons & Dragons
- An early one shows up in Basic D&D adventure X3 Curse of Xanathon. In the Backstory the Duke of Rhoona has issued several bizarre decrees, such as ordering that all taxes be paid in beer and that riders must face backwards on their horses. During the adventure the PCs witness the formal announcement of three decrees: (a) a declaration of war between Rhoona and the dwarven nation of Rockhome (b) combustible substances (e.g. lamp oil, candles and torches) cannot be burned at night and (c) all meat in the town can only be eaten by horses.
In Traveller, the Emperor reserves the option to issue an Imperial Warrant which overrides normal law and custom and proclaims that the holder be treated as if he was the emperor within the parameters written on the warrant. Usually this is for special missions especially those that might require jackbooting a lot of Obstructive Bureaucrat s. For instance, during the Fifth Frontier War, the Archduke Norris used an Imperial Warrant to engage in a mass firing of incompetent admirals in the Imperial navy.

Video Games

The page quote comes the Warhammer 40,000 game Dawn of War 2: Retribution, when a nameless Space Marine or Inquisitor initiates Exterminatus.
Played for laughs in the Jade's Story chapter of Tales of Fandom 2, in which Emperor Peony wants to go out into the city to investigate a possible coup being plotted against him, but Jade and Guy (quite reasonably) won't let him. The solution? Imperial Decree declaring that Jade and Guy are to accompany him into the city, which is met with exasperated obedience. (Anise too, but technically Peony doesn't have authority over her, so she was just tagging along for fun.)

Western Animation

Just before the closing credits of the Australian cartoon series Arthur! and the Square Knights of the Round Table, Arthur issues a royal decree that the audience tune in next time the drawbridge is down. ("...Prithee?")
On The Penguins of Madagascar, King Julien issues a decree that anyone who touches the royal feet will be banished from the kindgom forever. None of the other animals take it seriously, except for poor Mort, to whom the decree was issued for in the first place. After much hijinks and a near-death experience, Julien "undecrees" the decree.