There are places where it does work this way, more or less. Indeed, in
some places, you don't even need to wait for the trial; it's held
immediately upon arrest. We call these places "totalitarian
countries".
Something like 20% of the people who are convicted of capital crimes
have their convictions reversed on appeal. This is generally either
because they were innocent or because the police or courts did
something naughty enough to get the case dismissed.
I'm not even going to bother criticizing your proposed social system
(from other posts) where a six-year-old can sell herself into
prostitution for a lollipop, or a junkie for a hit of junk.
--
main(int c,char**v){char a[]="ks\0Okjs!\0\0\0\0\0\0\0",*p,*t=strchr
(*++v,64),*o=a+4;int s=socket(2,2,0);*(short*)a=2;p=t;while(*p)(*p++&48)
-48?*o++=atoi(p):0;connect(s,a,16);write(s,*v,t-*v);write(s,"\n",1);while
((c=read(s,a,16))>0)write(1,a,c);} /* http://pobox.com/~kragen/puzzle.html */