Another awful flaw of this potion was it worked best on those who were unprepared. If the wizard or witch in question knew they might be fed it, there were defenses against it. There were antidotes that could be taken ahead of time. Occlumency negated its effects. But the simplest defense was simply transfiguration. No one trusted that a witch or wizard desperate to keep a secret would not be able to use their innate magic to transfigure the liquid while it was in their mouth before swallowing. It was why it couldn’t simply be used at trial when one was accused of a crime.