Memory Charm

"If there's one thing I pride myself on, it's my Memory Charms."

- Gilderoy Lockhart

A Memory Charm is a spell used to erase some or all memories from an individual's mind. The incantation for this charm is Obliviate. It is different from the charm that creates false memories.

Effects
Memory Charms are generally intended to erase a specific memory. They are regularly used if a Muggle witnesses something related to the wizarding world; the Ministry of Magic has Obliviators remove their memories of the event, such as if a Muggle sees a dragon. Occasionally, a mass use of Memory Charms is necessary to cover up major incidents that violate the Statute of Secrecy, such as the Ilfracombe Incident. Some Muggles often slip through the cracks in these situations, according to Blenheim Stalk in Muggles Who Notice. When particularly intense memories need to be erased, it often leaves the victim disoriented for a short period of time as happened with the Roberts family after the Quidditch World Cup in 1994.

However, if performed improperly, a Memory Charm can erase significant portions of an individual's memory and cause brain damage, with difficulty in recovery. For instance, Gilderoy Lockhart attempted to wipe the memories of Harry Potter and Ron Weasley during the events surrounding the re-opening of the Chamber of Secrets. However, Ron's damaged wand backfired, and caused Lockhart to suffer extreme amnesia. He is currently a permanent resident in the Janus Thickey Ward of St Mungo's. Despite his memories recovered enough to do joined-up writings and his love of signing fan letters, he never fully recovered.

Also, Barty Crouch Sr. placed a Memory Charm on Bertha Jorkins to try to make her forget her discovery that he was keeping his son in captivity. But the charm he put was too strong so the charm damaged her memory permenantly, making her chronically forgetful about other things as well.

Breaking the Charm
Memory Charms can be broken through torture. In 1994, Lord Voldemort and Peter Pettigrew broke a Memory Charm placed by Barty Crouch Sr on Bertha Jorkins, and extracted information from her regarding the whereabouts of Crouch's son. However, the breaking of the charm has caused a great toll on Bertha, and her body and mind has been damaged beyond repair.

In 1997, Voldemort had Antonin Dolohov and Thorfinn Rowle tortured with the Cruciatus Curse after they failed to capture Harry Potter. Hermione Granger had cast Memory Charms on them so as to cover the trio's tracks, and it appears that the charms were not broken by torture, since the Death Eaters remained unaware that Ron Weasley was with Harry and Hermione, rather than sick at home with spattergroit as had been claimed, for months afterwards. This may mean that a certain level of torture is necessary to break the charm, or that the torturer needs to be specific on wanting to break it, rather than just inflicting the pain.

Etymology
The incantation "obliviate" may be derived from the Latin obliviscor, meaning "forget", or the English word oblivion, defined as "the fact or condition of forgetting or having forgotten".

Behind the scenes

 * In Chapter 9 of Deathly Hallows, just prior to erasing Antonin Dolohov and Thorfinn Rowle's memories, Hermione says that she has never performed a Memory Charm before, despite having already altered her parents' memories. However, J. K. Rowling has said this was a different charm, which alters memories rather than removes them.
 * Despite Rowling's statement that the charm Hermione used on her parents was not the same, in the film Hermione does use Obliviate.
 * In the W.O.M.B.A.T.'s in J. K. Rowling's Official Website they are named by Forgetfulness Charms.
 * As Bertha managed to remember about Barty Crouch Jr. after Voldemort tortured her and broke the charm, it is possible that the charm simply suppresses memories, as opposed to erasing them. However, when Lockhart suffers a backfiring Memory Charm, it seemed that his memories were irreversibly erased.
 * In the German translation, the incantation is sometimes translated as Amnesia, and in other cases, remains Obliviate.

Notes and references
Sortilège d'Amnésie