Could be that the spell has to be tied to a location, thus the secret being 'The Potters live at X, Godric's Hollow' rather than being 'The Potters'.

 

Is it? I don't argue if people write their fics with Trace on the wands and not the person because I'm not sure myself, but in my own interpretation, it's on the person. Canon is confusing in this regard.

In CoS Dobby casts the spell and Harry has no wand on him, yet the Ministry attributes the spell to Harry. If the Trace was on the wand, nothing should have been registered because the wand wasn't used. Or, the Trace is on either Harry/wand, but it's imprecise/has a radius, which would register Dobby's spell.

In PoA Harry's accidental magic on Marge doesn't trigger a warning letter from the Ministry if memory serves and I assume summoning the Knight Bus must be some sort of simple magic, although perhaps the Bus is excluded from the underage magic rules. Fudge must have let the Marge incident go because of Sirius' escape. But they did register it happening and again, Harry didn't use his wand, which points to either radius-based Trace or person-applied.

OotP fucks things up even further. Harry used his wand here and Fudge didn't much like him anymore so the letter gets sent. I'm pretty sure if Trace was radius-based, it would have picked up magic in GP12, unless Fidelius has that covered, which, while not a complete cop out, is a cheap explanation.

Speculating on people other than Harry doesn't help much either. We only have enough info about Ron and Hermione, possibly Draco. Ron and Draco live magical households. If Trace is wand-based, there's no issue until they get wands. Well, Ron uses Charlie's (or was it Bill's?) old wand for first two years, which, upon the original owner's graduation would have lost the Trace. If Trace was simply person-based, then it wouldn't have registered anything either. If Trace was radius based, the Ministry could have simply ignored the Weasleys because they had several underage kids at a time for years and Malfoys because Lucius could have bribed someone or whatever.

IIRC, Hermione says in the book she'd practiced some magic before coming to Hogwarts and this introduces even more little holes. Hermione's 11th birthday was in 1990. When and how is the Trace activated? Eleventh birthday? Then Hermione would have gotten a letter. The letter itself triggers it? Crossing the gates of Hogwarts? If it's on the wand, then it probably only has a deactivation date and no trigger date - 17th birthday, but that would mean Ollivander's wands would carry some enchantment that tunes the wand to the person's age so Trace knows when to shut down. Trace deactivating on person's 17th birthday makes more sense if it's person-based.

Basically, CoS pudding only makes sense if Trace had a radius, but then how big is that radius? One could imagine there would have been a moment with people like Dung or Tonks where they used a bit of magic while following Harry around in OotP, but nothing like that happens, so it's speculation.

PoA again makes sense if Trace has a radius, but could also fit being applied to a person. DH only tells us that Trace has finally stopped working and it's not an issue anymore.

Final argument against wand-based Trace is simple cheating. If all wandmakers everywhere apply Trace that's universally compatible with every magical government's surveillance spells, then okay. But if not, someone like Lucius Malfoy could have easily cheated the system by acquiring a wand with no Trace.

Basically, to me Trace makes most sense if I ignore inconsistencies in the books and slap it on a person. But above all, it's gotta be one of the most obvious real plotholes in the 'verse.

 

Here's the scene in DH where members of the Order polyjuice into Harry:

This would seem to support your idea that the Trace is on a person and there's an effective radius. But then in OotP Tonks casts a packing spell in Harry's room and he doesn't get a warning. If the effective radius is so small that it wouldn't detect a spell cast in the same room, then why would Moody be so anxious about not casting anything in the house?
This whole concept is a mess...

 

The only thing worse is the Hogwarts class schedule that somehow works with one teacher per subject and no Time-Turners, apparently.

 

Er, I don't think the trace is confusing at all. I think you guys just don't understand it >_>

The trace is on a person and records all magic used around that person. It cannot discriminate between casters. The Ministry sends an owl for a breach of the reasonable restriction for underage sorcery, not for every time they detect magic.

Accidental magic, both pre-Hogwarts and Aunt Marge: Not against the Reasonable Restriction for Underage Sorcery. No letter.

Hermione's pre-Hogwarts magic: Loophole in the Reasonable Restriction for Underage Sorcery -- they only get notice that they can't use magic at the end of first year. No letter sent.

Dobby's hover charm: Trace unable to discriminate between casters, Harry is attributed as no adult wizards were known to be with him at the time. Letter sent.

Goblet of Fire, Mr Weasley at the Dursleys: adult wizard was known to be visiting Harry to take him to the Quidditch World Cup, no letter sent.

Patronus Charm: a spell, not accidental magic, and no adult wizards known to be visiting Harry. Against the Reasonable Restriction of Underage Sorcery, letter sent.

Lumos charm: Harry already summoned to the Ministry to a hearing on underage magic for the Patronus charm, no letter sent as it would just be repeating his summons.

Tonk's packing charm: Harry already summoned to the Ministry to a hearing on underage magic for the Patronus charm, no letter sent as it would just be repeating his summons.

HBP, Dumbledore's apparition of Harry: adult wizard known to be visiting Harry, no letter.

Any others?

 

Does this mean that an adult wizard has to make it known they're visiting a minor?

 

He had to connect them to the Floo. One imagines he'd have done it then.

 

1. Harry in range of Killing curse cast by Wormtail on Cedric Diggory in the Little Hangleton graveyard (a very Muggle place); further spells cast upon Voldemort's re-embodiment include Cruciatus, Disarming Charm, Summoning Charm.

Are you thinking Wormtail called ahead?

2. Harry is in range of many other adult wizards in preparation of escaping 4 Privet Drive, yet Mad-Eye is having a hissy about the Trace- it would have been simpler to have Harry break the rule and be cited just as they were leaving, as the notice would be sent to him there and any others could be ignored. As it is, every spell he or Hagrid cast during their escape was detected, right? A Portkey would have worked better, as it could have taken him two steps outside one of their protected safehouses, and he would only have been cited while he was mid-transport. Side-along apparition would have worked better, particularly if performed by an official of the Ministry like Mad-Eye, Tonks, Kingsley or even Arthur Weasley.

The whole situation is the biggest plot-hole of the book; why would Dumbledore insist that Harry put himself into a dead-end cave like the Dursley's? There was no strategic benefit and a whole lot of downside that led to the death of two and maiming of another. I would have respected Harry more for denying Dumbledore's request and going by his own tactical instincts (if he had any).

Maybe it was really another test for Harry, one he failed- Dumbledore may have been trying to force Harry to make a leadership decision that contradicted his orders, to get him to grow up a little more. Instead he chose based on loyalty and sentiment.

 

Or they could have used this further violation of the law to say "forget the hearing, this time you are expelled". You'd think the Order people would be especially careful considering the Ministry's actions so far.

 

During the school term, and thus they won't be paying attention. The detectors will be pinging like anything but no one cares because that's expected while everyone's at school.

As for Privet Drive in DH: their worry is not Harry getting a letter. The Ministry has been compromised. Their worry is that the moment any of them cast a spell in the house they're dead: the Ministry has the ability to remotely drop all magical protections on a location at a moment's notice and send in their people (who will actually be Death Eaters as the Ministry is on the verge of falling) a moment later.

If they transported Harry via any kind of magic while Harry still had the Trace, the Ministry (which is not yet compromised enough to do stuff without a legal facade) would be able to use the excuse of Harry's protection to use their powers to crash whatever destination they go to. While Portkeys and Apparition may be impossible to track, Harry's Trace isn't.

 

I was found it a bit odd why, in PoA, Lupin would ride the Hogwarts Express when all the other Professors don't seem to travel to Hogwarts that way. Doesn't Hogwarts have Floo? How do McGonagall and the rest of them get to Hogwarts if they don't ride the Express with the students?

Of course, the easy answer to why Lupin is on the train is because "plot convenience: a teacher conveniently stops a monster from sucking out Harry's soul". Nevertheless, I always found this incident a little odd.

 

I've been under the impression that Lupin was either asked or volunteered to ride the train as a guard in case Sirius decided to show his face, the same as the Ministry's Dementors. The only part of that that seems to be 'plot convenience' is that Harry, Ron, and Hermione rode in his compartment.

 

Hell, maybe he did it for sentimental reasons.

 

Slughorn also rode the train once. Granted, he did it for obvious reasons, but still.

 

I know this one has been beat to death in a million and one indy!Harry stories, but its still a plot hole: Molly wondering where the platform is.

 

What's the problem? She's asking a question to elicit the location from her children to check that they know. It's a fairly common parental/educational tactic.

 

That's pretty good. I'm going to use that.

 

Damn. Occam's razor indeed.

 

This 'conspiracy' is still a thing? I thought people figured this out years ago.

 

I find Molly Weasley's defeat of Bellatrix more plausible than any kind of conspiracy involving her (let's be honest, the woman's a housewife, not a schemer), I just liked Taure's elegant explanation.