This is reasonably excused- Hermione would have been careful not to violate any rules, so she didn't attempt any spells at home. Instead she waited until staying in Diagon Alley the night before the train, or until she was on the train.

I was looking through 'A Sluggish Memory' in HBP because of this discussion. It occurred to me that what Dumbledore concluded was wrong.

He has the memory of Morfin being confronted by a teenage Tom Riddle, and then recounts that the Riddles were found dead and that Morfin, when confronted, declared with great enthusiasm how he had wiped the dirty muggles from existence. He was tried, convicted, sent to Azkaban, and only in the last months of life did Dumbledore visit him, using extensive Legilimency to uncover this buried memory.

Dumbledore's conclusion and the one Harry protested, was that Riddle must have Stunned Morfin, taken his wand, gone up the hill to kill the Riddles, come back, planted the wand on Morfin and implanted a false memory to cover his tracks, stolen the ring and left.

A simpler explanation: Riddle used the Imperius on Morfin, took the ring and then sent him up the hill to do the murders. His curse would be ignored by the Trace for happening in the Gaunt's residence.

I think JKR didn't want to give away the current scenario with Draco using the Imperius on Rosmerta, and so didn't use this more sound theory, which would also abide by the 'rules' of the Trace as described. If she'd wanted to hang the responsibility for a spell on the wand owner it would have worked, but only if she'd had Dobby steal Harry's wand in Book 2 to perform the Hover charm. Elf transport already operates under different rules than Wizard Apparation, so that's not a factor.

What's really interesting is that Dumbledore's mistake may have been acceptable as a consistent character flaw- that he would rather hang all the worst crimes on Riddle alone rather than think worse of Morfin Gaunt.

 

I always thought the method by which the Ministry detects magic worked something like how Hogwarts determines who gets sent acceptance letters.

According to a page on pottermore - and whether that makes it canon is another argument entirely - the Quill of Acceptance detects a child's first accidental magic, and their name is recorded in the Book of Admittance.

 

I really like the theory that it just detects magic and not who cast it. It fits most with the "pureblood bigots" idea and makes most sense.

 

I wonder when Trace activates - moment of birth or 11th birthday? Or does it have to be applied?

There are also going around ideas like trace on wands or on buildings inhabited by underage wizards. It doesn't sound like total absurd.

Charms as glamours or tracking ones are fading rather quickly. Wouldn't Trace applied on wizard act the same?

 

People always seem to mix up the detection issue with the legality issue. There's a lot of magic which surely falls into the "detected but not unlawful" category, Hermione's pre-Hogwarts magic being part of that. From what we know, the Reasonable Restriction on Underage Sorcery only applies from the end of your first year at Hogwarts onwards. I imagine the justification being that they assume pre-Hogwarts magic is all accidental magic, and it would be unreasonable to restrict that.

 

Maybe Dobby can intentionally "change" his magic to be mistaken for Harry's. It would explain how other adults could cast spells without the ministry sending notice.

 

It seems to be a location-based spell rather than a person-based spell, with it being limited to households without magical parents or guardians. Having to deactivate the Trace when students were in school would be a pain. It also explains how house-elf magic can be mistaken for Harry's magic. Similarly, that's why it's fine to assume that it isn't on magical households either -- there's no way to tell who cast the spell and it would be utterly useless in that case. Hogwarts-age Tom Riddle probably just figured this all out before trotting off to prune the family shrub.

As for how it's placed on Hogwarts students ... I don't know. Maybe it's activated the first time they pass through the castle doors.

Personally, I've always found the fact that the Trace cannot be placed on adult wizards to be the most interesting aspect. It suggests that either there are amazingly complex Ministry restrictions in place forbidding that, or that there is something else getting in the way. Knowing the Ministry of Magic, it's probably not the first one.

 

We know accidental magic does not trigger the trace and, considering they know exactly what spell is cast, I am guessing the trace only applies to magic that can be cast by a wand. It makes me wonder if they have to specifically pick spells to detect or it picks up any wand spells. I don't think it is a plot hole, just something that was never explored to the limits. Its not like Harry or his friends ever bothered to explore the limits of the trace.

From an ethics standpoint of muggleborn vs wizardborn, it is unfair that wizard households can use magic during their breaks at home and muggleborns can not. I understand that they argue that adult wizards are there to provide a hand to their kids, but it limits the education of the muggleborn giving them months at a time that they can't practice.

 

Do we? I assume you are referring to the blowing up of Marjorie Dursley in Book 3. It is true we don't see a letter that time, but Harry did run away right after and we know Fudge was covering for him.

As Fudge himself says...

In other words, the fix was in.

Further, we do know that the Ministry somehow knew to send in two members of the Accidental Magic Reversal squad to fix Marjorie. Given that I can't see the Dursleys ever calling the Ministry (see, for example, that the didn't for Dudley's tail) the Trace gives an explanation about how they knew who to send and that someone needed sending.

 

Ah, so the trace does accidental magic too. Seems like a short sighted solution, considering that Harry performed a decent amount of accidental magic before he even got a wand. Did they ever explore if it just doesn't record the magic of someone who is over 17? I don't think they ever mention how old Dobby is when he gets Harry his warning.

 

I consider detecting accidental magic very much a feature. It will let the wizarding world known if a muggleborn has just blown the Statute of Secrecy wide open with no wizarding parent nearby to do some hasty damage control. They can see the type of spell cast, where it was cast and workout how to properly react.

 

I don't see why there's a debate on it being personal vs. location based magic. It's, well, magic. There's no reason why those two options should be mutually exclusive.

How does that make it a short-sighted solution? Someone mentioned upthread that detection is not the same thing as legality, and I don't see why we should assume that the Trace is a purely punitive device. If anything, Tracing underage accidental magic is probably how muggleborns are found and put down for Hogwarts.

As for the Dobby situation, that depends on how you think the Trace works. However, as far as we know the Trace only applies to *humans* - yes, the Ministry doesn't exactly have the best species rights record, but extending it to other beings or even beasts is a gross violation.

Personally if I was writing the Trace as a computer program the process would go something like:
- Crawl the entirety of Britain for all manifested magic
- Was magic manifested in a registered Wizarding location? If yes, discard
- Was magic manifested in proximity to an adult witch or wizard (likely determined by chips in their wands)? If yes, discard
- Output the rest as "cases of underage magic", with metadata such as spell identification (or lack thereof). This infodump can be further parsed as "accidental" (unidentifiable spell) and "deliberate" (spell is identified)

Of course, magic isn't limited by little things like "processors", "RAM" or even "logic" so all four steps could conceivably be completed millions of times a second in parallel.

So Dobby's magic is reported because it's a) magic b) cast in a Muggle location and c) no adult wizard was found nearby. Finally d) the identification of a Hover Charm seals it as deliberate magic, and from there the Ministry uses regular detective methods to determine the culprit (it's Harry Potter's neighborhood).

On the other hand blowing up Aunt Marge and repelling Vernon are likely reported, because they fulfill a, b and c, but don't reach legal because they're accidental. They may conceivably reach other officials, like whatever department handles injuries caused by accidental magic (likely St. Mungo's).

I settled on this pattern because it's the only one that explains how Tom Riddle could get away with murdering his father and grandparents. The Trace can't be specifically personal (i.e. its notification can't come as "Tom Riddle did magic"), because the Ministry doesn't seem to realize he was ever even there. The Trace can't even have left a notification at all, because as far as we know the court never wonders at the burst of underage magic that just happens to coincide with the Riddles' deaths. So it was disabled by something - either the Gaunt Shack counted as a Wizarding location, or the proximity of an adult wizard (or perhaps an adult wizard's wand) stopped it from triggering.

 

Like I said, there's nothing mutually exclusive about the concepts. Asserting it's 100% one or the other is kind of silly. It's magic. It's adaptable to the intended need.

I'm...not entirely sure what this is all about, seeing as this is a thread to discuss the workings of the Trace. "We know what it is" doesn't answer the question "how does it work?". We know Incendio lights shit on fire, but does it lower its target's combustion point to room temperature? Does it generate and transfer a huge amount of heat, causing the target to burst into flames? Does it conjure flames and dump them on the target? Does it matter? Probably not, but in a thread asking how it works I'd hope someone wouldn't try to shut down all conversation.

Sent from my D5803 using Tapatalk

 

No, my argument is "because it's magic, things that seem mutually exclusive are not necessarily so. And seemingly contradictory 'logic' is open for discussion". Because it's *magic*, and so a spell cast on a person can also be a spell cast on a location.

Do you have a book scene or recap where The Trace Wizard Committee showed up and cast a specific targeted spell on an individual called The Trace?

Because if not, you're inferring and drawing conclusions.

Unless you have an explicitly stated explanation for how the specific, individual-targeted Trace spell conveniently did not register Tom Riddle's...ah...extracurricular summer activities. Or maybe you actually think Mafalda Hopkirk Sr. got a notification that *three* Avada Kedavra's were cast by or in proximity of an underaged wizard and simply shrugged about it?

And honestly I'm not sure how my comment confuses you, what with statements like "if I were designing the Trace like a computer program" and the example with Incendio. I'll repeat myself, though; "it's cast on a person" is not an answer to the question "how does X spell work".

 

No, but there's this:

and this:

Given the excerpts provided, any and all magic performed around an "under-seventeen" is detected. We also know that Tom Riddle killed his father at sixteen. If he did this during the school year ministry officials might not have even looked at whatever they detected because it was during the school year.