Why isn't this potion (the truth potion) used in trials? Wouldn't it make it much easier to solve mysteries?
True, using the truth potion would mean people would not be able to lie when they were being questioned. However, from what we have seen in the books, Veritaserum does not completely allow the drinker to think on his/her own. This means s/he would only give the information s/he was asked for. If the person was not asked something, some potential decision-changing information might never reach the jury.
Another point is that the truth potion does not seem to allow the drinker's mind to think ahead: A thing which often makes those trying to hide something nervous and vulnerable to slip ups. Under the influence of Veritaserum, those being questioned would not feel the pressure of trying to hide incriminating information and if, as I discussed before, they were not asked for that information, it would never reach the court.
Although Veritaserum could be used when the person being questioned is untrustworthy, it would be better to allow them to speak before using the potion. After the potion was administered, the court could see which was lie and which was not.
We must consider also whether drugging someone with Veritaserum is moral. In America, we have the Fifth Amendment which allows people to withhold information that might incriminate them. People have a right to privacy. Veritaserum is one of the most invasive potions that could be introduced to the legal system.
And after everything else is considered, we must still take into account the following:
Is truth always fact?
Not always. In fact, very rarely given that truth is often a matter of opinion. Many times people rephrase things to alter their meaning or importance. Sometimes people think they are telling the truth, but really aren't.
An example, please?
Take Sirius Black's situation. They had tons of witnesses. All of them said Sirius Black killed Peter Pettigrew. All of them said they saw him do it. All of them probably thought they were telling the truth, too. Using Veritaserum on them would not have changed the outcome one bit, except perhaps for the worst: More weight would be given to the information witnesses presented under the influence of Veritaserum; they can't "lie" so what they say must be "truth." Sirius Black could have been worse than dead before sundown.
