Well, as the trace is present upon an underage Wizard before he comes of age, hence the Ministry being able to detect underage magic immediately whenever the underage Wizard does it, I still don't quite understand the following situations.

(Is it traceable by location or by person?)

When Dobby did the Hover Charm (Year 2), the Ministry couldn't differentiate whether it was indeed Dobby or Harry Potter who performed it. Suggesting the Ministry detect some kind of magic at a particular address they have on record as being resident to an underage wizard?

However, when Arthur Weasley visited Harry Potter at Privet Drive (Year 4), he did a lot of magic, including magically dodging the teacups Mr. Dursley was throwing as him, and as well as performing an anti-Engorgment charm to return Dudley's tongue to a normal size. So how come did the Ministry differentiate who actually performed magic?

Moreover, at The Burrow, what happens if an underage Harry or Ron performs magic? Can't simply the elders say they performed magic instead?

Update: After reading two answers below I'm still confused. If magic is location based, Tonks, Madeye and Dumbledore all do a lot of magic at Privet Drive and Harry is never caught. Additionally, can't Harry do magic at The Burrow and Mrs. Weasley simply say she did it instead. Whereas if Magic is person based, obviously it isn't because they could differentiate that Dobby performed the magic and not Harry.

  • well it isn't a matter of how strict or not, its a matter of consistency and plot integrity. if the author tells us its supposed to be like this, i.e., underage magic is such, then it should be consistent and make sense throughout the series. Commented May 24, 2012 at 1:20

3 Answers 3


The Trace is location based; they can tell when magic is performed within the vicinity of an underage wizard, and they know where it happened. In the case of Harry, since he's the only registered witch or wizard living in the vicinity of Privet Drive, then any magic in that area is attributed to him. In the case of Wizarding families, where it's not possible to know precisely who performed magic, the Ministry relies on the parents of underage wizards to prevent them from using it.

This is, I believe, all covered in the books at one point or another. Unfortunately I can't provide quotes right now because I don't have access to them.

  • Well location based? But then why can't/doesn't Harry Potter do magic at the Weasleys then? It would be so easy for Molly Weasley to say, she did it. Commented May 24, 2012 at 1:23
  • 2
    And again, how could Mr. Weasley, Tonks, Madeye, Dumbledore perform magic at Privet Drive in front of Harry, and Dobby couldn't? Commented May 24, 2012 at 1:32
  • @ManikSethisuwan I've provided all the information about the Trace that I remembered from the books. Is it consistent? No, but there's not much I can do about that. There's nothing in the books that addresses those problems. Commented May 24, 2012 at 8:16
  • thank you @Anthony Grist. i guess they, JKR had to make things harder for Harry Potter. Commented May 24, 2012 at 9:47
  • @manik-sethisuwan In order of the Phoenix, they could have traced Tonks magic and created more trouble for Harry right? Commented Jan 13, 2017 at 8:33

The hover charm Dobby does in Chamber of Secrets only gets Harry into so much trouble because it is done in the presence of a muggle (Mr & Mrs Mason, potential customers of Mr Dursley, who he is entertaining), which is a different offence than performing under-age magic outside of school.

When in a house with no other non-magical-aware muggles, it's down to the parents of the child to enforce the no-magic-outside-of-school law, because, as you say, the ministry can't tell who in the house performed the spell (though if the child is the only witch/wizard in an otherwise muggle household, it's pretty obvious; so how Hermione got away with practising spells before the start of their first year in The Philosopher's Stone is a puzzle!). I can't remember the canon reference to this, but I'm sure it's mentioned in one of the books.

To answer the specific question though: It's entirely possible that the ministry knew Arthur Weasley was visiting Harry (Arthur does work for the ministry, after all). The reference to this is he uses his contact from floo network regulation committee to connect the muggle house (4, Privet Drive)

  • 1
    Aunt Marge's visit is in Prisoner of Azkaban, not Chamber of Secrets, so you're confusing the two instances. Harry gets a warning for the Hover Charm offense, so doesn't really get him into much trouble at all (the Muggles - a builder and his wife that the Dursleys are entertaining - don't even witness the actual magic, they only see the results of it). The incident with Aunt Marge is overlooked partly because it wasn't intentional but mainly because of the Sirius Black situation. Commented May 22, 2012 at 8:22
  • 2
    Because it was before their first year, I would attribute Hermione's spellcasting to the Ministry assuming it was nothing more than accidental magic, like when Harry accidentally released the snake at the zoo.
    – Izkata
    Commented May 22, 2012 at 10:42
  • 2
    I still don't get it. Alright in Order of the Phoenix, just hours after Harry Potter is expelled (then suspended) from Hogwarts due to doing a Patronus Charm, a few hours later the Advanced Guard is there at his house (to escort him to HQ). Tonks and Madeye do a ton of magic there. Of course, the Dursleys weren't there. Then again, next year (Half-Blood Prince), Dumbledore is there in the living room doing tons of magic, in front of the Dursleys. So you know, it's quite confusing. Commented May 24, 2012 at 1:17
  • 1
    Yep, agree with that!
    – Nick Shaw
    Commented May 24, 2012 at 12:43
  • 1
    @ManikSethisuwan I don’t see any contradiction here. The Trace is location-based, but there’s somehow a way to detect whether adult Wizards are present, which could also be the cause of the magic. This has been used multiple times in the later books, however, Harry did not exploit this when he was at the Weasley’s home, because he didn’t know it (and he wasn’t keen on breaking the law). The ministry did not spot the presence of Dobby at the first incident, like almost every Wizard has a blind spot when it comes to House Elfe’s magic. That is very consistent throughout the books.
    – Holger
    Commented Apr 16, 2019 at 11:01

There is no trace. Harry and Co. were found because Harry said, "Voldemort" which according to the Death Eaters was tabooed. Despite the fact that Rowling screwed up underage magic throughout the books.

  • 5
    There definitely is a Trace, it's mentioned multiple times throughout the books and applies to all underage witches and wizards (those under seventeen years old). You are, however, correct that Harry, Ron and Hermione were found in Deathly Hallows due to the Taboo on saying Voldemort's name, but that was after the Trace on Harry had been lifted (he'd come of age the day before). That's all very irrelevant to this question though. Commented Aug 28, 2013 at 12:39
  • The question is about magic at privet drive, not around the cafe in deathly hallows Commented Jan 13, 2017 at 8:27

Not the answer you're looking for? Browse other questions tagged or ask your own question.