How do wizards protect themselves from memory charms?

Question

Memory charms seem incredibly easy to pull off; Lockhart built his career off them. They can also be incredibly subtle and discreet; like when Hermione uses "Obliviate" on her parents with just a whisper.

I can only imagine the abuse possible with such charms in our world (corporate espionage, making an enemy believe you were family, rewriting life-insurance policies...), and very limited legitimate use (forgetting a traumatic memory is the best I can come up with).

How do wizards protect their memories when each and every enemy has the desire to wipe them out, and the means to do it with naught but a whisper?

Answer 1

The Shield Charm might be able to block it.

Protego, the Shield Charm, can block certain types of spells. It’s never stated to block Obliviate specifically, but it’s a possible protection.

“He was still having trouble with the Shield Charm, though. This was supposed to cast a temporary, invisible wall around himself that deflected minor curses; Hermione managed to shatter it with a well-placed Jelly-Legs Jinx.”
_{^{- Harry Potter and the Goblet of Fire, Chapter 31 (The Third Task)}}

It blocks the Stunning Spell and Accio, so it’s possible it might block a Memory Charm as well. The cases we know of where wizards (not Muggles) had Memory Charms cast on them, the one who was Obliviated seemed to be either unaware or helpless - we don’t see anyone who knows it’s coming and tried to protect themselves.

The Weasley twins’ enchanted Shield clothing might also work.

Another form of shield that may possibly work is the Shield clothing sold at Weasleys’ Wizard Wheezes, which blocks minor to moderate hexes or jinxes, but its effectiveness against Memory Charms isn’t mentioned.

“So we’ve expanded into a range of Shield Cloaks, Shield Gloves …’ ‘… I mean, they wouldn’t help much against the Unforgivable Curses, but for minor to moderate hexes or jinxes …”
_{^{- Harry Potter and the Half-Blood Prince, Chapter 6 (Draco’s Detour)}}

If they do work against Memory Charms, wizards could wear them as protection against having their memory wiped even if they’re not aware when Obliviate is being cast.

Memory Charms can be broken (by torture, likely other ways too).

The Memory Charm can also be broken, though it’s not clear how easy this is.

“We could have modified her memory? But Memory Charms can be broken by a powerful wizard, as I proved when I questioned her. It would be an insult to her memory not to use the information I extracted from her, Wormtail.”
_{^{- Harry Potter and the Goblet of Fire, Chapter 1 (The Riddle House)}}

The Dark Lord used torture, but there may be other methods as well.

“He tortured her until he broke through the Memory Charm my father had placed upon her. She told him I had escaped from Azkaban.”
_{^{- Harry Potter and the Goblet of Fire, Chapter 35 (Veritaserum)}}

Dumbledore was able to break through Memory Charms by using Legilimency, but it’s unclear if Morfin himself got the memory back or if Dumbledore was only able to see it himself, not restore it.

“But he had this real memory in him all the time!’

‘Yes, but it took a great deal of skilled Legilimency to coax it out of him,’ said Dumbledore, ‘and why should anybody delve further into Morfin’s mind when he had already confessed to the crime?”
_{^{- Harry Potter and the Half-Blood Prince, Chapter 17 (A Sluggish Memory)}}

Most of the time when Memory Charms are used, no one tries to break through it, but it seems to be at least possible. The only instance where we see it not working is on Lockhart, when he accidentally erased his own memory with Ron’s broken wand.

Many would still likely be vulnerable to sudden Obliviation.

While there do seem to be ways for wizards to protect themselves against being Obliviated, that would require them to be cautious enough to want to. Though we don’t know the extent that every wizard would be concerned about it, it’s unlikely that they’d all take precautions like wearing shield clothing. People like Mad-Eye Moody would take every precaution possible - but there are also people like Bertha Jorkins, who was a bit dim and not very careful. We don’t know how many wizards wear some sort of shield clothing (though we know the Weasley twins sold 500 with huge orders still being made). Blocking it with a spell would only work if they know it’s coming, so that’s not a certain protection. If shield clothing prevents blocks Obliviate, that’d be a wizard’s best bet - but of course it’d only work for wizards who were cautious enough to use it.

Answer 2

The point, surely, is that wizards can't protect themselves against memory charms.

In Chamber of Secrets, it is initially established that Professor Lockhart is the expert in the use of this type of charm. He uses them to confund Muggles, so that they support his claims - made in his many books - to have overpowered a whole mess of dangerous magical creatures in his early career.

But when push-comes-to-shove, Lockhart tries to use the charm on Harry Potter and Ron, and (by a mischance) the charm backfires, destroying his mind. If it were possible to use some form of incantation or talisman to protect yourself, Lockhart - who knew all about this type of charm and was an expert with them - would have known how to do that, and would have done it, to protect himself.

After using that charm to resolve a major plot point in volume 2, JKR couldn't then have someone in the next book - nor any later book - demonstrate a method that would have made a nonsense of that crucial scene in Chamber of Secrets. Having established that even the best expert on memory charms was vulnerable to them, it wasn't possible to later undo what had been so early established.

The fate of Lockhart is later revealed, in Order of the Phoenix, when we encounter him in hospital at St Mungo's with his mind still shattered by the after effects of the memory charm. Even the best healers have no answer to this type of charm, and Lockhart remains in a memory damaged state even after several years of treatment. His presence in the hospital implies, even though it's never explicitly stated, that not even Dumbledore - the most powerful wizard of all - could heal him.

Dumbledore's ability to go play tiptoe-through-the-tulips in the mind of Morfin Gaunt, who was memory-charmed by Riddle, implies there may be a distinction between two separate states: that there is a difference in a case such as Gaunt's, who had only a limited modification, altering his memories of just a single event, from the case of Gilderoy Lockhart, whose entire mind was blasted by the charm.

Answer 3

Lockhart was an expert in memory charms. This does not necessarily mean that memory charms are easy.

“Harry, Harry,” said Lockhart, shaking his head impatiently, “it’s not nearly as simple as that. There was work involved. I had to track these people down. Ask them exactly how they managed to do what they did. Then I had to put a Memory Charm on them so they wouldn’t remember doing it. If there’s one thing I pride myself on, it’s my Memory Charms.

_{-Harry Potter and the Chamber of Secrets}

There is an inconsistency with Hermione's memory charm.

“You’re the boss,” said Ron, sounding profoundly relieved. “But I’ve never done a Memory Charm.” “Nor have I,” said Hermione, “but I know the theory.”

_{-Harry Potter and the Deathly Hallows}

But she used a memory charm on her parents before that.

---

A remembrall will turn red if someone forgets something. If a remembrall turns red, and you remember having a sudden disorientation during the day, you can deduce that you were memory-charmed. Also, memory charms are not necessarily permanent. They can be walked back as Dumbledore did to Morfin Gaunt, who was memory-charmed by Riddle. Having a monthly memory-check-up can be helpful too.