It's in the constitution, dna has freed many convicted beyond a doubt. And sometimes new evidence comes up.
Why are criminals who have been found guilty beyond a reasonable doubt allowed to have a retrial? I believe that it's a waste of time and money.
It goes back to the saying of innocent until proven guilty. If the jury cannot find a individual guilty beyond reasonable doubt then as the Constitution says that individual is entitled to a retrial. Yes, it is very expensive but the important thing to remember that it is not a justice system
I have been through our so called justice system. Cops will lie, people lie, our justice system stinks to high heaven.