At the beginning of a criminal trial, the defendant is vested with what is called the ”presumption of innocence.” Despite the fact that he or she is in court after having been arrested means nothing at that point. The jury must presume the person is innocent and that must continue until the prosecution produces evidence that not only overcomes the presumption but that clearly establishes guilt “beyond a reasonable doubt.”
While the Court defines “reasonable doubt” for jurors, the complicated language often leads to results that seem to defy what is shown by the evidence. In that case, jurors will decide with their gut feelings rather than following the strict language of the law. Two celebrated cases illustrate this. In the recent case of Florida v. George Zimmerman, the majority of people polled believe the defendant should have been convicted of something; the jury acquitted. In the older and more notorious case of California v. O. J. Simpson, the jury acquitted despite public opinion that the evidence of guilt was overwhelming. Then, unfortunately the opposite is true. Innocent people are convicted and go to prison or suffer the death penalty. DNA evidence in recent years has proven that.
So, while jurors may be confused by jury instructions to the extent that they may ignore them, the American system is still the best in the world, despite its flaws.