OOP: Problems and questions about veritaserum

[mr_misnoid]

No: HPFGUIDX 65620

Does anyone else think about 80% of the plot would be meaningless 
with a little application of veritaserum?

Just one exmaple, what is the point of witnesses and doubting people 
at a trial, Harry's in the beginning for example, when they could 
have just given him a little veritaserum and realized everything he 
said was true. What about Black when he was first arrested? What 
about anyone ever who disbelieves someone about anything major and 
imortant? Why did Umbridge even try and pretend to sneak the serum to 
Harry, why not just order him to take it?

There are about a million things in the book that would be made 
immediately pointless and meaningless if someone just took a little 
veritaserum.