Book 3- Snape; Neville; Sirius

[Steve Vander Ark]

No: HPFGUIDX 8767


> Shouldn't they have given 
> Sirius the chance?  They didn't have anything to lose-- if Harry 
and Hermione 
> were Confounded, Sirius would say that given the truth potion.

Real world reason? Because JKR thought up Veritaserum for book 4, so 
it didn't "exist" in the HP universe in book 3. So if we want to use 
that logic, we'll say that within the context of the books, 
Veratiserum was not yet available or was beyond even Snape's potion 
making skills until 1994. Maybe Snape had heard of it, that the 
Ministry was really going to be monitoring the use of this stuff, and 
he knew that THAT was one potion he just HAD to know how to make, 
especially since it would have come in so HANDY in that whole Sirius 
Black business (that dratted Potter MUST have had something to do 
with it, he just KNOWS it, if only he could MAKE him tell the truth). 
So he took a class during the summer, a grad level truth potions 
class, and now he carries that precious bottle around with him at all 
times, just in case...except he forgot to carry it to the Third Task, 
so he had to go get it.

Steve Vander Ark
The Harry Potter Lexicon
which has an excellent page devoted to potions...
http://www.i2k.com/~svderark/lexicon