13 Harry Potter Plot-Holes (That Were Totally Solved)

7. Why Wasn't Truth Serum Used On Secret Death Eaters?

The "Plot-Hole"

If genuine truth serum exists in the Wizarding World, why wasn't it used by the Ministry Of Magic to find out which of Voldemort's allies were genuine Death Eaters and which were acting under the Imperius Curse as they might have claimed?

Wouldn't it have been a useful asset in the aftermath of the war to make sure the remaining Death Eaters were rounded up?

The Solution

JK Rowling actually confirmed that the Ministry DOES use Veritaserum, but that it's in no way infallible:

“...skilled wizards can avoid its effects by using antidotes and charms. A gifted Occlumens could also resist Veritaserum."

And since Voldemort wouldn't have chosen bad wizards for his closest supporters, they were probably well-equipped to escape the effects.