The Universal Declaration of Human Rights, article 11, states: "Everyone charged with a penal offence has the right to be presumed innocent until proved guilty according to law in a public trial at which they have had all the guarantees necessary for their defense."
In this less-than-perfect world in which we live, the scenario may look something like this:
In San Diego County, 94% of felony charges result in either a conviction at trial or the defendant agreeing to "plead guilty" in exchange for a sentence they can tolerate. For example, to someone facing a serious charge carrying the possibility of a lengthy prison sentence, signing a plea to a lesser charge and serving perhaps only a few years sounds pretty good…even if they are innocent, and especially if they have already been sitting in county jail for a long period of time. This is how people who may truly be innocent end up with felony convictions, parole headaches, and the social stigma of having pled guilty to a crime.
The wheels of justice turn slowly indeed...and sometimes they fall off altogether.