Imperius Curse

"Total control. I could make it jump out the window, drown itself, throw itself down one of your throats..."

- Barty Crouch Jr. as Alastor Moody on a spider he had put under Imperius Curse

The Imperius Curse is one of the three Unforgivable Curses. When cast successfully, it places the victim completely under the caster's control, though a person with exceptional strength of will is capable of resisting it. This makes it unique among the unforgivable curses, as it is the only one of them with a known, reliable (depending on the victim's will) method of resistance. The curse's incantation is Imperio.

Effects
"It was the most wonderful feeling. Harry felt a floating sensation as every thought and worry in his head was wiped gently away, leaving nothing but a vague, untraceable happiness. He stood there feeling immensely relaxed, only dimly aware of everyone watching him."

- Harry Potter under the Imperius Curse

Unlike the other Unforgivables, being subjected to the Imperius Curse - when adequately cast - is not an unpleasant experience, in fact, quite the opposite; the victim of an Imperius Curse is placed in a calm, trance-like state in which all feeling of responsibility and anxiety is banished (drawing parallels to the real-world phenomenon of hypnosis, which is also often portrayed in fiction - albeit inaccurately - of being capable of placing someone under the complete control of another by placing them in a theta state). However, when Harry was Imperiused, he believed that his curse may not have been very strong, thus the sensation from casting a more powerful Imperius Curse may be more intense than the known account.

An adequately Imperiused being is placed under the caster's total control and may be directed to do anything the caster wishes, including crimes such as murder, political corruption, embezzlement, and so on. Also, whilst under the caster's control, the curse may also endow the victim with whatever skills that are required in order to complete the task at hand, such as increased strength or allowing them to cast spells far above their level. For example, an Imperiused Neville Longbottom was able to perform a series of "quite astonishing gymnastics" under the curse that he would not normally be capable of.

If the Imperius Curse is performed poorly, then the victim would have their mind addled, an example being Muggle Junior Minister Herbert Chorley. It seems the damage is long-lasting, as Chorley was sent to St Mungo's Hospital for Magical Maladies and Injuries to recuperate. This is likely due to the fact powerful, dark magic may leave irreversible biological damage, such as when George had his ear cursed off permanently.

Resisting the Imperius Curse is possible, but requires great strength of will and character. Harry Potter, Barty Crouch Sr. and Barty Crouch Jr. each learned to resist the curse after being subjected to its effects, though the latter two took quite a long time before building the said resistance, and in Barty Sr.'s case, resistance against Voldemort's powerful curse has seemingly caused mental damage. Resisting the Imperius Curse is similar to Occlumency, which requires a great amount of willpower, though it is unknown if Occlumency would actually work against the curse.

It is possible for someone who has been Imperiused to place others under the curse as well. For example, Madam Rosmerta, who had been Imperiused by Draco Malfoy sometime during the 1996–1997 school year, was able to place Katie Bell under the Imperius Curse in an attempt to deliver a cursed necklace to Albus Dumbledore. It is also possible that the Death Eater Yaxley used the Imperiused Pius Thicknesse to place other high-ranking members of the Ministry of Magic under the curse in order to facilitate the overthrow of Rufus Scrimgeour.

When a correctly cast Imperius curse is terminated - for whatever reason - the victims become themselves again, as happened after the final defeat of Voldemort and the Death Eaters in the Battle of Hogwarts, when all of the people across the country who had been Imperiused by him or his supporters were released from the spell. Also, any pain that the curse has negated by the pleasant sensation would return, along with any other pain that the victim suffered for the duration of the curse.

Creation
The Imperius Curse was invented during the early middle ages by dark witches or wizards. The curse was created for the coercion and brainwashing of others into slavery.

Legal status
"The Cruciatus, Imperius and Avada Kedavra Curses were not made "unforgivable" until 1717."

- Albus Dumbledore

After the Wizards' Council was reformed into the Ministry of Magic, tighter restrictions were placed on the use of certain kinds of magic. The Imperius Curse was deemed by the Ministry to be dark magic, and, along with the Cruciatus and Killing curses, were declared "unforgivable" in 1717. The use of any of these three curses on a fellow human being would result in a life sentence in Azkaban, unless there is sufficient evidence that the caster did so under the influence of another's Imperius Curse; this tends to be a factor that many Dark Wizards abuse and lie about when they were facing prison, particularly after the First Wizarding War.

During the First Wizarding War, when Barty Crouch Sr. was in charge of the Department of Magical Law Enforcement, he fought violence with violence, and legalised the three Unforgivable Curses for Aurors against the Death Eaters in order to win the war. This was repealed once the war was over, as it was no longer necessary. It was also at that time that many Death Eaters, such as Lucius Malfoy and Walden Macnair, claimed that they had served under Lord Voldemort only because of the Imperius Curse. While their claims were accepted, the Ministry has gone as far as to assign several personnel to determine who is truly under the curse, and who is lying to escape punishment; however, they were not perfect in capturing deception, as Malfoy and Macnair, along with several others, still eluded justice.

In the 1994–1995 school year, Barty Crouch Jr., under the disguise of Alastor Moody, showed these three curses to his fourth year classes on spiders despite the Ministry's disapproval. Later, in fact, he claimed that he had permission to perform the Imperius Curse on students in order to teach them how to resist it.

When Lord Voldemort took over the Ministry, the three curses were once again legalised: this time every wizard and witch had the right to use them as they please. In fact, they were practiced in Hogwarts as part of the curriculum in the Dark Arts class under the tutelage of Professor Amycus Carrow. After Voldemort's death and the revolutionising of the Ministry under Minister Kingsley Shacklebolt, the three curses were once again forbidden, and many people under its influence felt like they were coming out of trances.

History of use
"Scores of witches and wizards have claimed that they only did You-Know-Who's bidding under the influence of the Imperius Curse. But here's the rub: how do we sort out the liars?"

- Barty Crouch Jr on the Imperius Curse's controversy.

Death Eaters made use of the curse in both the First and Second Wizarding Wars to force innocent people to do their bidding. For example, Lucius Malfoy used the Imperius Curse to force Broderick Bode and Sturgis Podmore to try to steal a prophecy from the Department of Mysteries in 1996, and Yaxley placed the Imperius Curse on Pius Thicknesse as part of the plan to take over the Ministry of Magic in 1997.

Ironically, many Death Eaters, such as Lucius Malfoy, avoided imprisonment in Azkaban after Voldemort's first defeat in 1981 by claiming that they had been under the Imperius Curse. As such, it became the Ministry's work to determine who was lying, even though many "victims" managed to deceive them.

Harry Potter and Albus Dumbledore speculated that Merope Gaunt may have used the Imperius Curse on Tom Riddle Sr. to force him to marry her, although Dumbledore thought it more likely that she used a Love Potion.

Other known uses

 * Herbert Chorley, a Muggle Junior Minister, was the victim of a "poorly-performed Imperius Curse." The resulting symptoms included impersonation of a duck in public, which required him to be removed from society temporarily and transferred into St. Mungo's.

Etymology
This curse takes its name from the Latin imperiosus, meaning "commanding, mighty, and powerful", or imperio, which means "to rule".

This is also the root of imperative, which is the form of a verb that acts as a command: this is certainly what the imperius curse achieves.

Behind the scenes

 * In the 1995-1996 school year, Professor Severus Snape wanted an essay on how to resist the Imperius Curse from his sixth year class, and to his displeasure, he found they were poorly written, calling them tripe.
 * In the film adaptation of Harry Potter and the Goblet of Fire:
 * the Imperius curse appears to give the victim's eyes a milky, glazed appearance which is not mentioned in the books and would decrease the curse's effectiveness, since it would be easily detectable. However, it's possible that this is a sign of a poorly or hastily performed curse, or one where the victim is actively resisting.
 * when Barty Crouch Jr. (disguised as Alastor Moody), puts the Imperius Curse on the spider, he directs it movements with his wand, including having it float and hover in midair, as if a Levitation Charm was put on it.
 * In the part 2 film adaptation of Harry Potter and the Deathly Hallows:
 * the Imperius curse appears to be a mist that the victim smells and gets under the caster's bidding. It also appears to leave the victim in a slightly intoxicated, elated state.
 * the incantation is said to be Imperius, as opposed to the proper incantation Imperio. It is unknown why this is.
 * when the Imperius curse wears off on Bogrod, Ron replaces the initial curse.
 * This spell does not appear to be illegal in the handheld versions of LEGO Harry Potter: Years 5-7, as Severus Snape teaches it to Harry in place of the Occlumency lessons from the book and film.

Appearances

 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (film)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 2
 * Harry Potter and the Deathly Hallows: Part 2 (video game)
 * The Tales of Beedle the Bard
 * Harry Potter: Spells
 * LEGO Harry Potter: Years 5-7

Notes and references
Imperius-Fluch Maldición Imperius Sortilège de l'Imperium Komennuskirous Maledizione Imperio Империус Imperius