You do know the constitution can be changed don't you?
The jury system is seriously flawed and is the reason for many of the injustices you rant about yet you defend it. It is based on the opinion of 12 people whether or not a person in guilty not the actual evidence since juries for the most part have no expertise evidentiary procedure, forensic science or any other relevant area of study that allows them to actually determine the guilt or innocence of a defendant.
I don't defend it. Unlike your imaginary right to own guns, it's clearly spelled out in the constitution as every citizen's right. However, only 2% of criminal cases are heard by juries. 58% are plea bargains and most of the rest are either dismissed or heard by a judge.
The alternatives aren't any better. Judges are political creatures, who put retaining their office above doing justice. Look at this judge who just sentenced the guy to six months for drunken frat sex. He'll probably get recalled because his judgement was politically unpopular. I can't imagine that professional tribunals would be any better.