When I was in the Boy Scouts, a local judge came to speak with us about the legal system. I asked a similar question and he admonished me that innocent people never wind up in court. He explained that every person who is in a trial (criminal or civil) is guilty of something. A judge's job was merely to determine if the prosecution or plantiff was correct about what the defendant was guilty of. He was very annoyed that ignorant people, who had never been to law school, kept spreading this nonsense that some defendants were innocent.