Why Do Innocent People Plead Guilty?

The Sixth Amendment guarantees a fair trial to every American accused of a crime. But trials are no longer the basis of the criminal justice system. A US Supreme Court majority has said it's not trial by jury that determines "who goes to jail and for how long," it's plea bargaining. More than 90 percent of criminal cases are decided by plea bargains — and many people plead guilty — even when they're innocent. Do they know what they're doing?  Are the law and the justice system rigged to favor the prosecution?  What would happen if every defendant demanded a jury trial?