"You're lying!"
A Slytherin student couldn't help blurting it out.
After Madam Pomfrey had exposed them for faking their injuries and ordered them out of their beds, the other Slytherin students had been glaring at them like traitors.
Speaking up now was risky, but sitting there doing nothing was clearly riskier.
Manus ignored him. The question was never which side could argue the other into silence.
Instead, Manus continued addressing the two professors:
"If you have reservations about using Veritaserum, I can offer magical assistance. I know a spell that, when cast on an area, makes anyone who enters it able to speak only the truth—much like drinking Veritaserum."
The second-circle Enchantment School spell, Zone of Truth, created a magical area that resisted lies. Centered on a point within casting range, it covered a sphere with a fifteen-foot radius. Until the spell ended, creatures inside it could not deliberately lie.
Like Veritaserum, however, affected creatures could sense the effect and choose not to answer questions they would ordinarily answer with lies.
They could be evasive or dodge the point when answering, so long as what they said remained true.
"Oh?"
The two professors were surprised and intrigued. Didn't that sound like a spell version of Veritaserum?
The reasons Veritaserum could not be used in formal interrogations were complicated. Officially, though, the objection had always been the same: while taking effect, it could also damage the drinker's brain.
That was only a possibility. The side effect arose only when an imperfectly brewed batch was used in excessive doses, but it still gave anyone unwilling to drink it a plausible excuse.
What changes might a spell bring if it could replace Veritaserum entirely without any side effects?
That might be a question for the wizards of the Wizengamot to worry about. Here