It seems to me that Harry could have saved himself a lot of grief if he had allowed people to see his memories (either through extraction or Occlumency). For instance:

  • He could have proved Lucius Malfoy placed the diary in Ginny's basket.
  • He could have proved Sirius's innocent (with the memory of Wormtail's confession).
  • Most importantly, he could have proven Voldemort was back.

Maybe it would have made for a less exciting story, but it sure would have made his life easier.


I'm going to say that canon is inconsistent when it comes to memories. There are instances of memories being used as evidence in the Harry Potter series.

In Chamber of Secrets, the diary Horcrux is actually a preserved memory of sixteen-year-old Tom Riddle; Dumbledore uses the remains of the diary Horcrux to establish that Voldemort is active again and attempting a comeback.

"Dumbledore's been driven out of this castle by the mere memory of me," [Tom Riddle] hissed. (emphasis J.K. Rowling, Chamber of Secrets -- Chapter 17)

and then:

"A clever plan," said Dumbledore in a level voice, still staring Mr. Malfoy straight in the eye. "Because if Harry here--" Mr. Malfoy shot Harry a swift, short look "--and his friend Ron hadn't discovered this book, why -- Ginny Weasley might have taken all the blame. No one would ever have been able to prove she hadn't acted of her own free will" . . . "Very fortunate the diary was discovered and Riddle's memories wiped from it. Who knows what the consequences might have been otherwise. . . ." (Chamber of Secrets -- Chapter 18)

Dumbledore was prepared to use the diary with its memories preserved as evidence toward Ginny Weasley's innocence. However, Harry destroyed the diary with the basilisk fang, effectively wiping all memories from its pages.

Throughout Half-Blood Prince, Dumbledore uses memories in the Pensieve as evidence to show Harry Tom Riddle's/Voldemort's actions, motivations, crimes, and plans.

In Half-Blood Prince Dumbledore recounts to Harry how Morphin Gaunt was falsely convicted of the murders of Tom Riddle Sr and Tom Riddle Sr's parents in the Riddle House. When the Ministry came to question Morphin Gaunt, he confessed to the murders on the spot, therefore not requiring either Veritaserum or Legilimency (magic that extracts memories). Dumbledore was able to procure a visit with Morphin Gaunt at Azkaban in the weeks before Morphin died; Half-Blood Prince says:

"But he had this real memory in him all the time? [Harry]

Yes, but it took a great deal of skilled Legilimency to coax it out of him," said Dumbledore, "and why should anyone delve further into Morphin's mind when he had already confessed to the crime? However, I was able to secure a visit to Morphin in the last weeks of his life, by which time I was attempting to discover as much as I could about Voldemort's past. I extracted this memory with difficulty. When I saw what it contained, I attempted to use it to secure Morfin's release from Azkaban. Before the Ministry reached their decision, however, Morphin had died." (Half-Blood Prince -- Chapter 17)

This is an example of a memory being used as evidence by the Ministry of Magic; although they had not reached a decision, they were considering it. It also implies that the Ministry of Magic uses both Legilimency and Veritaserum (another way of gaining memories, via potion) to collect evidence to be used in criminal proceedings.

In Order of the Phoenix, Snape says,

[Legilimency] is the ability to extract feelings and memories from another person's mind--" He then explains, "The mind is not a book to be opened at will and examined at leisure. Thoughts are not etched on the inside of skulls, to be perused by any invader. The mind is a complex and many-layered thing, Potter . . . or at least most minds are . . . " He smirked. "It is true that those who have mastered Legilimency are able, under certain conditions, to delve into the minds of their victims and to interpret their findings correctly. (Order of the Phoenix -- Chapter 24)

In Goblet of Fire, Dumbledore says,

"The Longbottoms were very popular. The attacks on them came after Voldemort's fall from power, just when everyone thought they were safe. Those attacks caused a wave of fury such as I have never known. The Ministry was under great pressure to catch those who had done it. Unfortunately, the Longbottoms' evidence was -- given their condition -- none too reliable." (Goblet of Fire -- Chapter 30)

Yet, Barty Crouch Jr. was convicted of the torture of the Longbottoms and sentenced to life in Azkaban, on what appears to be testimony from the Longbottoms themselves, which would be their recounting of their torture presumably from memory.

Regarding the original question, as others have mentioned, Lucius Malfoy was not witnessed putting the diary into Ginny Weasley's cauldron, so there would be no memory of that incident by anyone other than Lucius himself. Perhaps Lucius's own memory, if it had been secured, could have been used as evidence against him at a criminal trial. And, yes, Harry could have quite possibly proved Sirius's innocence. Regarding the return of Voldemort, Cornelius Fudge was determined not to believe Harry, despite reasonable and overwhelming evidence that Voldemort was back. I believe he would have rejected a retrieved memory from Harry if one had been obtained. It wasn't until the end of book five that Fudge accepts Voldemort's return. Harry was not the only one to see Voldemort at the Ministry of Magic following the battle at the Department of Mysteries in Order of the Phoenix. Dumbledore dueled Voldemort and was aware of his return. Furthermore, Voldemort was witnessed at the Ministry in the atrium by Cornelius Fudge and an Auror named Williamson. As well, Order of the Phoenix indicates that there was a large group of people in the atrium at the time Voldemort was sighted.


Well, I haven't seen anything canon to answer this.. But I suspect it relates to several things:

  • Memories can be altered.. Look at Slugworth... He was a bit ham-handed at it, but Dumbledore hints that others may not be so.
  • It opens up a serious privacy concern... If it's permissible, could it also become mandatory? "Potter! I think you did X in potions class! Mind-dump time!"
  • Is memory accurate? Harry is taken by how detailed memories are... But, then, memories, even without being intentionally altered, are likely to be colored by the perceptions of those that remember them.
  • If it was admissible, the first thing any good plotter would arrange would be for someone to only see certain things, or to see things in a way that they could be interpreted multiple ways... Or get really good with memory wiping spells.

No formal back-up to these, but they seem consistent with the rest of the Potter universe; I always favored Veritaserum for the same reason, but the same flaws are inherent in it. However, here's what J.K Rowling had to say about Veritaserum.

Veritaserum works best upon the unsuspecting, the vulnerable and those insufficiently skilled (in one way or another) to protect themselves against it. Barty Crouch had been attacked before the potion was given to him and was still very groggy, otherwise he could have employed a range of measures against the Potion - he might have sealed his own throat and faked a declaration of innocence, transformed the Potion into something else before it touched his lips, or employed Occlumency against its effects. In other words, just like every other kind of magic within the books, Veritaserum is not infallible. As some wizards can prevent themselves being affected, and others cannot, it is an unfair and unreliable tool to use at a trial.

Sirius might have volunteered to take the potion had he been given the chance, but he was never offered it. Mr. Crouch senior, power mad and increasingly unjust in the way he was treating suspects, threw him into Azkaban on the (admittedly rather convincing) testimony of many eyewitnesses. The sad fact is that even if Sirius had told the truth under the influence of the Potion, Mr. Crouch could still have insisted that he was using trickery to render himself immune to it.

  • 5
    +1 for the first bullet point - Professor Slughorn was not skilled at manipulating memories, yet all that Dumbledore could get from him was the false one - and the final point about Veritaserum having the same flaws
    – Izkata
    Nov 27 '11 at 3:02
  • 3
    IRL criminal investigations, witness memories have proven to be terrible records of even very traumatic incidences. People misremember the face/ethnicity/clothing color of the suspect. Some people even put people at the scene who weren't actually there. And memory quickly becomes contaminated once witnesses are exposed to interrogation techniques, such as trying to put together a sketch of the suspect's face (the reconstructed face made by the sketch artist/program will replace the actual face in the witnesses' memory). Nov 27 '11 at 16:41
  • 3
    @KeithHWeston - ES: I thought for sure that it was your interpretation of it. It didn’t make sense to me to be able to examine your own thoughts from a third-person perspective. It almost feels like you'd be cheating because you'd always be able to look at things from someone else's point of view. MA: So there are things in there that you haven't noticed personally, but you can go and see yourself? JKR: Yes, and that's the magic of the Pensieve, that's what brings it alive. (Part II of ?) Jan 4 '12 at 19:08
  • 2
    ES: I want one of those! JKR: Yeah. Otherwise it really would just be like a diary, wouldn’t it? Confined to what you remember. But the Pensieve recreates a moment for you, so you could go into your own memory and relive things that you didn't notice the time. It’s somewhere in your head, which I'm sure it is, in all of our brains. I'm sure if you could access it, things that you don't know you remember are all in there somewhere. [Thought this was interesting -- source URL: accio-quote.org/articles/2005/0705-tlc_mugglenet-anelli-3.htm ] Jan 4 '12 at 19:09
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    @KeithHWeston - Oh, as my professional background is in law enforcement, I couldn't agree with you more on points 1 and 4. You're absolutely spot on. There's a reason why we have to plan for all these remote contingencies. Privacy and warrants and search and seizure are all huge big deals. In Potterverse, law enforcement does not seem to err on the side of innocent until proven guilty. I'm sorry -- I didn't mean to come barreling in for the sake of stomping on your theory. But put it this way. . . to me, it's the legal system, not the "justice" system, and for good reason, IMO. :) Jan 4 '12 at 22:24

I can't find my book six right now, but I'm pretty sure Dumbledore said he tried to use one of the memories he obtained to free its owner, but the owner died before he succeeded. I take that to mean that, at least in some cases, memory can be used in evidence. Memories can, however, be altered, as we saw to some extent with Slughorn (though his was poorly done), and I believe Dumbledore said it can be more professionally done - like Tom Riddle did to his Uncle. Moreover, memories are extremely private. What's to stop the court/examiners/...? from, say, examining every aspect of Harry's life while they're at it? How much trouble would Harry be in if they found out half of what he did?

To address your first example, no one actually noticed Lucius put the diary in Ginny's cauldron. Would it appear in a memory if no one noticed it?

I would guess that for Sirius, since they thought he was so powerful and evil, they would assume he had altered Harry's (and the others') memories.

As far as Voldemort goes, they (Fudge at least) REALLY didn't want to believe it. If Harry and Dumbledore presented evidence in the form of a memory, they would argue that Dumbledore had made it up.

  • About the second paragraph: From how JKR describes the pensieve and how I understand that (see comments on K-H-W's answer), it would seem that it would, as long as someone at the very least saw it with the corner of an eye without realizing.
    – Egor Hans
    Mar 19 '19 at 11:24

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