Guilty Until Proven Innocent?

This thINK post contains spoilers for The Tenth Circle.

People are wrongly convicted all the time for major crimes they did not commit. Innocent people are forced to live many years in prison because of people not telling the truth. How is that fair?

In The Tenth Circle by Jodi Picoult many big crimes have been committed but no one knows what really happened or who committed the crimes because everyone is lying. Trixie accuses her ex-boyfriend, Jason, of rape. When she is questioned she does not want to look like a slut so she lies about half of her story. Jason keeps saying that he did not rape her: that it was consensual. No one knows who to believe. Then, more evidence is found that reveals that a date rape drug was used, but Jason swears up and down that he did not give her the drug. Soon Jason is found dead at the bottom of a bridge. Was it suicide or murder? And if it was murder, who was the murderer? The whole book is one big case of "he said, she said," and many of the things said are lies.

After reading this book I wondered if this happened in the real world. According to this website innocent people are convicted all the time. This article explains that the main cause of wrongful convictions are eyewitness accounts. Why are eyewitness accounts considered reliable? An individual's memory can be changed easily by a number of factors. People can be persuaded into believing something really happened when really they do not remember. Why are we so quick to throw someone in prison if we do not have the proper evidence?

If so many innocent people are put into prison, then why is our legal system based on the ideal "innocent until proven guilty?" In these cases it seems more like guilty until proven innocent.