Veritaserum

"Three drops of this and even You-Know-Who himself would spill out his innermost secrets."

- Severus Snape threatening Harry Potter with Veritaserum.

Veritaserum is a powerful truth serum that is most commonly used in interrogation. The potion effectively forces the drinker to answer any questions put to them truthfully, though there are some methods of resistance. Use of the potion is strictly controlled by the Ministry of Magic.

Description and effects
Veritaserum is clear, colourless, and odourless and is almost indistinguishable from water. According to Severus Snape, the potion must mature for a full lunar phase, and is quite difficult to produce. It can be mixed with any drink, and three drops are a sufficient dose to make the drinker "spill out his innermost secrets", although this is only an example to say that it forces the drinker to tell the complete truth to any question asked to him/her.

Resistance and limitations
Despite being the most powerful truth serum there is, it can still be resisted through different methods, including the taking of the antidote and Occlumency, and it is no more reliable for wizards than a polygraph machine is for Muggles, and for the exact same reasons. Because some wizards and witches can resist its effects and others cannot, Veritaserum is "unfair and unreliable to use at a trial", and thus cannot be used as definite proof of guilt or innocence, much like polygraph machines are for muggles.

Another weakness is that the victim only states what they believe to be true, so the victim's sanity and perception of reality also factor in during interrogations. This is the main reason why Barty Crouch Jr.'s testimony was not credible, as he was clearly insane.

Known uses
Veritaserum was used on Barty Crouch Jr. in June of 1995, when Albus Dumbledore discovered that Crouch was disguised as the Defence Against the Dark Arts teacher, Alastor Moody. Severus Snape also threatened Harry Potter with it earlier that year, suspecting that Harry had been stealing supplies from his storeroom necessary to brew Polyjuice Potion, prior to the discovery that Barty Crouch Jr. was the one who stole the ingredients to disguise himself as Alastor Moody.

Dolores Umbridge attempted to use Veritaserum on Harry the following year, but to no effect, both because Snape had presented her with a fake potion and because Harry only pretended to drink it (he dumped it in one of her plants while she was occupied). Umbridge later asked for more Veritaserum after Harry broke into her office to contact Sirius Black, but Snape said it would take a month to make more and suggested she use poisons on Harry if the situation were very grave, all the while taunting her about using the entire bottle last time, rather than the necessary three drops. Dolores suspended Snape, and proceeded to tell Harry the Cruciatus Curse would have to do, but Hermione Granger, who was also present, intervened and pretended to tell Umbridge the truth.

Though not used, in the 1995–1996 school year, Horace Slughorn, the Potions master, created Veritaserum for his first sixth year class as an example of one of the many potions that they should be able to concoct after completing their N.E.W.T. examinations. Later that term, when Harry suggested the usage of Veritaserum on Slughorn to get a certain memory, Dumbledore rejected that idea, knowing that Slughorn can resist it with an antidote, and Dumbledore did not want to use force or coercion.

Rita Skeeter used Veritaserum on Bathilda Bagshot while interviewing her about Albus Dumbledore and his family for her biography of him.

Etymology
The name comes from the Italian veritas, meaning "the truth", plus the Latin serum which means "fluid" or "liquid".

Author's comments
J. K. Rowling has said that Veritaserum "works best upon the unsuspecting, the vulnerable and those insufficiently skilled (in one way or another) to protect themselves against it...just like every other kind of magic within the books, Veritaserum is not infallible". For this reason, she explained that even if Sirius Black had been given the opportunity to testify to his innocence under Veritaserum, the Wizengamot likely still would have found him guilty by claiming that Sirius was using trickery to be immune to it.

Behind the scenes

 * In the film version of Harry Potter and the Goblet of Fire, Snape says that Veritaserum would make even Voldemort spill his darkest secrets. This is most likely an exaggeration meant to intimidate Harry, as Occlumency can be used as a defence against it. However, in the book Snape merely states that it would make Harry spill his innermost secrets, which would almost certainly be true.
 * In Harry Potter and the Goblet of Fire, when Barty Crouch Jr. was being interrogated at the end of the year, Dumbledore shook three drops of Veritaserum into his mouth while he was unconscious. In the film version, Snape poured the entire contents of the bottle right into Barty's mouth while it was forced open in a struggle.
 * In the film version of Harry Potter and the Order of the Phoenix, Dolores Umbridge used Veritaserum on Cho Chang to force her to betray Dumbledore's Army by exposing the location of their meeting place, the Room of Requirement. The character who betrayed the D.A. in the novels, Marietta Edgecombe, was omitted from the film. Cho's unwilling betrayal was also the cause of her split with Harry Potter in the film (as Harry had no idea of Cho being under the potions influence), whereas in the novel, it was her continuing grief over Cedric Diggory, irrational jealousy of Hermione Granger, and defence of Marietta's betrayal.

Appearances

 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (film)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Order of the Phoenix (video game)
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Half-Blood Prince (film)
 * Harry Potter and the Deathly Hallows
 * The Queen's Handbag

Notes and references
Veritaserum Veritaserum Totuusseerumi