Harry Potter and the Prisoner of Azkaban

By J.K. Rowling

Yet another series of unfortunate events that could have been easily avoided with a simple solution: a single truth-potion. They have those in this world. Sure, they’re hard to make, but if one had been given to Sirius Black after he was falsely accused then his name could have been cleared in an instant and the real culprit could have been publicized. In fact, why aren’t those thing a staple in the magical criminal justice system? Seems like they’d prevent literally all miscariages of justice.

Also, why is Hermione overwhelmed and sleepy with the timeturner? Unless there are rules about that thing’s use that are never communicated to the reader, there’s nothing stopping her from just using it to take naps and get extra study time.