It is not the job of the jury to fill in the blanks left by the prosecution. Rather its role is to decide based on the evidence presented inside the courtroom and to find guilt beyond a reasonable doubt, a heavy burden to meet but necessary when unanimously agreeing to send someone to prison for perhaps the rest of his life.
One can not help but think of the classic 1957 black-and-white film, 12 Angry Men when picturing what may be going on inside a jury room. In that film, when the jury first votes among themselves all but one juror, played by Henry Fonda, believes the defendant to be guilty. But in the end, plot spoiler here, Fonda talks them into seeing things his way, and the man is found "not guilty".
No one knows what goes on inside a jury room. Deliberations are secret. That is the way it should be. Although some jurors may choose to give interviews afterward, perhaps it would be better if they kept it amongst themselves. A juror's decision whether to convict or acquit should not be colored by having to face queries from the press and public later.
The jury's role is that of the conscience of the community. We look to the jury as the voice of reason, of common sense. It has been said that the collective wisdom of twelve men and women getting together to decide someone's fate is greater than the sum of its parts. That this collective wisdom occurs, when each juror brings to the table his or her life experiences and knowledge.
Of course, the burden of proof is on the prosecution to prove beyond a reasonable doubt the guilt of the accused. The defense does not have to prove the innocence of the accused. That is the beauty of the American system of justice.
A criminal prosecution is not like a civil lawsuit or what you see on all The People's Court type TV shows. Those shows deal with civil matters in small claims court where the burden of proof is an entirely different standard. In those cases, what is at stake is money damages only, not going to prison. In small claims court, the amount of money at stake is a relatively small amount. Hence, the name small claims court.
The burden of proof on those TV shows is a "preponderance of the evidence," a much easier burden for the plaintiff, the one bringing the claim, to meet. There is no prosecutor in those types of cases. Just one person against another without lawyers.
In civil suits like on Judge Judy, a "preponderance of the evidence" standard is often roughly described as tipping one way 51%. That's not the the burden of proof standard for a criminal trial where guilt must be found "beyond a reasonable doubt" and where the "intent" of the accused plays a pivotal role.
Juries are instructed to follow the law and in the Blagojevich brothers cases, over a hundred pages of jury instructions were read by Judge James Zagel to the jury right before deliberations began. That is a lot to absorb, especially for nonlawyers.
Yes, jurors represent the conscience and the common sense of the community. They do the best they can with what they are given. At times, juries have engaged in what is called jury nullification. According to Wikipedia, "jury nullification occurs when a jury in a criminal case acquits a defendant despite the weight of evidence against him or her." The Wikipedia entry goes on to say, "Jury nullification is thus a means for the public to express opposition to an unwanted legislative enactment."
Wikipedia says that "jury nullification is the source of much debate. Some maintain that it is an important safeguard of last resort against wrongful imprisonment and government tyranny. Others view it as an abuse of the right to a jury trial that undermines the law." The Wikipedia entry concludes, "Nevertheless, there is little doubt as to the ability of a jury to nullify the law."
The power of a jury is awesome. We can only pray it is used wisely. Our mothers often told us, "Let your conscience be your guide." So be it for the jurors, too.